CEnvironment: fixes
* Use proper conversion flag and check for flag support on system
* return right variable from CEnvironment::win32ConvertWToUtf8
* add support for VS2012 debug runtime
* don't try to initialize std::string and std::wstring with NULL pointer
[win32] Replace usage of pgwin32_putenv with our CEnvironment::putenv
[win32] Finally remove win32env.c
[win32] Use CEnvironment in WIN32Util.cpp
Use CEnvironment in cdioSupport.cpp
Simplify and unify environment usage in CUtil::GetHomePath
Unify Environment usage in emu_msvcrt.cpp