Combine output of ProcSat_Altimeter.py

[JessicaMeixner-NOAA]

When running ProcSat_Altimeter you cannot always process the entire period of interest, therefore we need to combine these outputs. We can use cdo mergetime, however then information such as satelite name which is a variable with character is lost. We should have a quick routine to merge in time processes values and retain information such as satellite name.

[JessicaMeixner-NOAA]

@sbanihash had an idea where we could update ProcSat_interpolation.py
to input multiple time chunks/files and even satelites instead of worrying about combining things.

[sbanihash]

@Ghazal-Mohammadpour , it might be helpful to look at how satlist is used in modelSat_collocation.py .