- GetEnv for Windows returns null-terminator in string
- GetEnv for POSIX could crash with a null pointer to std::string conversion
- FindBlender logic path simplified
This removes SystemString, SystemChar, etc.
All filepaths and log strings are assumed to be UTF-8,
with conversions to UTF-16 for Windows APIs as appropriate.
Updates amuse, athena, boo, kabufua and nod