added function documentation and removed two obsolete functions

automated determination of which days to aggregate for any given month

tweaked climatology calc function to return list of GRASS map names

switched from truncating to rounding mean LST back to integer

wrote function to download HDF files for given tile/year/day-range

wrote function to look up local HDF files for given tile/year/day-range

wrote function to encapsulate LST loading and QC-adjustment

added initial Python+GRASS code to download and aggregate daily LST