Following a few coverity scans, several inconsistencies / potential bugs have been fixed. Since my commit to picojson got merged, the newest version of picojson has been taken.

Code cleanup in libsmet, better min/max for ILWR in PNGIO, support for color, description, units, min and max in smet files in SMETIO and smet2agr. The SMET specifications will still have to be updated to reflect these recent additions, though...

More includes cleanup and code cleanup in the plugins (getting rid of the "stationindex" thing that was pretty much deprecated in all plugins)

The STD_PRESS spatial interpolation algorithm has been extended and can now deal with multiple input stations (with 2 different methods for handling this case). The Imis plugin now reads the air pressure and convert it to station air pressure (instead of sea level). Otherwise, improved error messages in libsmet and documentation / minor code cleanup.

Introduced the basic structure that will be required to build a new plugin to read Matlab files prepared by the OSHD project/service. This is not usable yet but should come quite soon.

The SUPPR filter can now take as argument a file containing a list of station IDs and timesteps where the parameter should be deleted

In order to add 3D grid reading/writing methods to the plugins, the whole architecture of IOInterface has been changed: this is not a purely virtual class anymore, it now always implements the "nothing implemented here" exception. This makes the plugins more compact (there is no need to implement empty methods for what the plugin can not support) and much clearer. The documentation and template have been changed acoordingly.

Several exceptions have been renamed in order to be more generic (ex: instead of FileNotFound -> NotFound) and their text has been modified accordingly. The GSN plugin now reports the errors with more relevant details (invalid sensor name, no permissions).

Code cleanup and fix for IMIS: now the ENET stations receive the number 1 for the automatic stations instead of 0.

All the PNGs that we written were corrupt: the first line of data was missing. This has been fixed. for NetCDF, the ability to calculate the altitude from the pressure (and sea level pressure) has been added with a controlling key. This is not very precise but this could help for troubleshooting problems when no DEM has been provided (such as with ECMWF data sets).

The CNRM plugin can now be enabled and properly works. Its documentation has been updated and improved. The NetCDF plugin can now read DEMs using various schema/conventions and its documentation now matches the code. A few more MeteoGrids have been defined that are required for meteorological model outputs and for some future spatial interpolations (ISW_DIR, ISW_DIFF for example). The PNG plugin creates a few more EXIF fields in order to make it very easy to integrate in google earth (but it seems that google earth does not like indexed pngs). A bug computing the geolocalization of grids coming from NetCDF has been fixed (all grids were slightly off).

The basic operators have been implemented in Grid2DObject and Grid3DObject as well as DEMObject (with the proper update strategy). 

In order to suppress the risk of out of date "ncols, nrows" and since these were redundant with Array2D<>.nx/ny, they have been suppressed and it is therefore now mandatory to rely on the getNx/getNy/getNz getters. This is much safer but impacted quite a lot of code... 

Adding a new meteo parameter: the cloud transmissivity TAU_CLD defined as iswr_meas / iswr_clear_sky (ie the potential radiation computed at ground level with a standard atmosphere, see Iqbal 1983). This parameter is already used by the AllSky_LW and PotRad generators and properly handled by the PNG plugin. The PNG plugin can now also properly output a hillshade (as MeteoGrids::SHADE).

Some documentation bugs have been fixed (multiple links definitions for doxygen). The config.dox file has been updated (in order to remove the warnings for obsolete keys). The parameter exclusion feature has been documented and now supports both a space delimited external file or by keys such as WFJ2::exclude = TA RH HS

better file structure: all the classes purely focused on data storage (such as grids, dates, etc) have been moved into a "dataClasses" directory. All subdirectories are nhow named similarly to the classes and methods: the words after the first one are capitalized.

A new pre-processor variable has been defined: MSVC so the pragmas for VC++ are now properly enabled for msvc only. An improper include for MSWIN has been removed.

The WIN32 pre-processor variable has been renamed in MSWIN since this is more logical on Win64 (and to avoid potential conflicts). Some headers have been cleaned up in the process (in Timer.h/.cc). A new method has been moved from Config to FileUtils: isAbsolutePath. Some extra features (support for offset in hours) added to NetCDFIO.

Several bugs have been fixed: in the AllSky generator, the cloudiness was still forced to 0.5 (as for debug). The data creators were also called *after* the generators, thus making it impossible to used a created data in a generator. 

The placeholders have been put in place (but commented out) for the cloudiness/tau_cloud/clearness index support in MeteoData. It seems that Kt=clearness index might be the proper way to go, but this is still a messy field. Some comments have been added in the code to clarify the use of such parameters.

Fixed a segfault when using PNGIO (allocating the wrong number of elements). Small cleanup in Graphics.

The cmake files for compiling with LibXML++ have been updated since they would not work with more recent Linux (but we should consider dropping LibXML++ and only rely on LibXML2 in order to reduce the dependencies and package finding mess). The special points are now called POI (Points of Interest, like for a gps device) in order to make them more familiar.

The filters have been slightly simplified, some IOUtils functions optimized (after reading an interesting post about the handling of rvalues), a bug fixed in PNGIO on Windows, the macros MAX and MIN are not used anymore (relying on std::max and std::min instead). A new data generator is on its way to generate HNW from HS differences (but this will require architectural changes to the DataGenerator).

Fixing some warnings for Visual C++ and also using ostringstream instead of stringstream when appropriate

The info string for the spatial interpolations was not being cleared between calls, leading to ever increasing content... Otherwise, using an ostringstream instead of stringstream in PNGIO and fixed a typo in the documentation.

More size_t fixes (ie trying to be consistent) and a bug was found when spatially interpolating using a few specific algorithms that would not reset their internal vectors between two calls (thanks Matteo for helping uncover this bug!)

fixing some of the warnings found on Hera (sorry for not noticing before). All the size_t / unsigned int stuff will have to be addressed later

My previous commit was terrible... it simply made it impossible to define optional keys. This has now been fixed but required a change in the API. So, don't use Config::nothrow but IOUtils::nothrow instead.