COMMON: MSVC doesn't know about #warning
COMMON: _byteswap_xxx is defined in stdlib.h
COMMON: isprint() needs ctype.h on MSVC
GRAPHICS: DECLARE_SINGLETON already puts its argument into namespace Common

Doing it twice raises an error on MSVC (declaring an object outside
the "current" namespace, which ends up being Common::Common)
SOUND/VIDEO: Some disambiguation fixes that trip MSVC

MSVC doesn't do implicit conversions from int to float/double,
for example
COMMON: Some more MSVC peculiarity
COMMON: Some more .string() -> .generic_string() fixes
DOCS: Add Michael D to the contributors list
KOTOR: Add Difficulty Setting