- Enable 'language' feature on unix targets.

The sdl version of the function 'SetLanguageIDs' is very limited, comparing to the win32 counterpart, as it will try to accept only the language codes (ie 'enu', 'fr', 'ptb', etc). If a different string is provided, zdoom will default its language to English.
Fix LZMA compilation on GCC with position-independent code (PIC) generation enabled

EBX register is used Global Offset Table in PIC
http://www.greyhat.ch/lab/downloads/pic.html
Merge branch 'language_sdl' of https://github.com/edward-san/zdoom
fixed compilation with latest LZMA SDK on Windows.

LZMA SDK recently added an #include <windows.h> to its headers, meaning it's no longer safe to include its headers globally in platform independent files.
The following changes were necessary:

- rename DWORD type in zipdir.c
- add USE_WINDOWS_DWORD and reorder includes in file_7z.cpp
- wrap LZMA decoder stream into a local struct that's declared anonymously in files.h and adjust files.cpp for this change.
Merge branch 'master' of https://github.com/rheit/zdoom
Merge remote-tracking branch 'gzdoom/master'