This is necesary for the packaging (it is much beter to have an
"inishell-apps" folder in /usr/share than an "applications" folder)

This addresses issue 834: files that will be read from a METEOPATH
should be stripped of their path otherwise the path appears twice. On
the other hand, this means that since there is no link to the METEOPATH
(or similar variable), we don't know which directory the files belong
to, so we can not validate anything (beside non-empty file name). This
is better than generating a wrong configuration file but still not
perfect...

The virtual stations are given as "VSTATIONx", not "POSITIONx"!
Moreover, more links to the online documentation have been added and the
syntax highlighting (in the PreviewWindow) now supports the coordinates
specifications (otherwise, coordinates provided with ";" were shown as
comments).

And some basic validation in the xml (somehow the full regex does not evaluate properly when provided in the xml)

It is not perfect in the sense that the 2DInterpolation section must be created anyway, independently of the use of spatial resampling or not. The same applies to the Grids2D configuration frame. A message is shown to the user, explaining when these should be used...

But still lots more to do!

Fix doubled elements because of faulty XML references parsing with nested include files _and_ references. A little bit of the new meteoio.xml and some file cleanup for it