Changes to gr2sr to support terrain correction of seasat -- WIP
Fix problems using capitalized macros for endianness

BIG_ENDIAN and LIL_ENDIAN changed to ASF_BIG_ENDIAN and
ASF_LIL_ENDIAN because of conflicts with other software
Merge branch 'devel' of https://github.com/khogenso/ASF_MapReady into devel
Merge branch 'devel' of https://github.com/asfadmin/ASF_MapReady into devel