Updating the ini files to the newest generators' syntax in MeteoIO. Added a policy specification in CMake to avoid a warning (we required at least a relatively old version of cmake and this policy is now always set in newer versions...)

There was a problem on osX that it would only compile against the SDK version of the system doing the build. As I was often lagging way behind, this was not a problem but now that I've updated to the latest version, older versions of osX could not run the binaries. Now compatibility with SDK version 10.13 (High Sierra) is enforced and cmake is required to be at least 3.0.2.

Unfortunatelly, the results of the tests still depend on the machine it is running on... Moving to a new CI server means new reference files (although these are now much closer to the results I get on my own desktop).

Added the drifted mass to the available gridded outputs (if snowdrift is enabled, otherwise it will be nodata)

Improving the FindMeteoIO.cmake and FindLibsnowpack.cmake: it now gives priority to installations close by and should better handle when it is not found

Snowdrift was not working anymore since the required normals were not computed on the wind fields' DEM. An incorrect information message when running without saltation has also been fixed.

Some minor differences were found in the reference files (just a few cases at ~1e-3 relative errors, most much below). This could come from an update on the server or from the changes to the wind vw,dw vs u,v in MeteoIO.

TRying to only perform ctest_memcheck on the alpine3d binaries, not on the bash scripts that evaluate the energy balance, etc

Overwriting albedo in SnowpackInterfaceWorker.cc when SW_MODE != BOTH leads to inconsistent results. In those cases, the calculation internally uses the albedo parameterization, but independent of that, the output files would report glacier_albedo.

After the update of the CI server, the tests have some small numerical differences (the biggest relative difefrence is 1e-3, then a few at 1e-4 and then all below 1e-6).