support loading both Skew-T and Altitude data

[savelov]

I noticed that in https://github.com/opengribs/XyGrib/blob/master/src/DialogLoadGRIB.cpp#L167 it is not allowed to load both Skew-T data and altitude data, however allowing that enables Skew-T profiles down to ground (see attached screenshots) I remember using ZyGrib with both, hence suggesting to remove this restriction. I have tried commenting out the logic in source code, it works correctly, however increasing the GRIB file size - may be this is the reason for restricting it? Please advise

[savelov]

I have made a fix for it in https://github.com/savelov/XyGrib/commit/4a36f23db49a3d76aa981dc51704749aa92d3cef but not sure the reason why this was originally disabled - may be due to performance issues?

[norulz]

It was a performance issue. There are other performance control mechanisms on the server now so I will check about removing this. David