* Added s_rem(s) for getting the remaining bytes in a stream
* Added s_rem_out() macro
* Fixed 15bpp pointer error checking
* Combined the 512 and 2048 bit certificate sending code paths
* Other detailed comments and logging added following MS-RDPBCGR
Constants from MS documents (MS-RDPBCGR etc) moved out of
common/xrdp_constants.h into includes named after the documents.
Similar includes moved from sesman/chansrv to the common area.