- Shut up GCC aggressive optimizer warnings.

From what I can see, GCC would miscompile the involved loops, because the index variable is 'signed int' and the multiplication with an unsigned would cause signed overflow (undefined behavior). Change the index variable type to 'unsigned int' to expect unsigned overflow (conformant to standard).
- Simplify CMake GCC and Clang checking.

Introduce the variable 'ZD_CMAKE_COMPILER_IS_GNUC(XX)_COMPATIBLE' and replace any occurrence of '"${CMAKE_C(XX)_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C(XX)_COMPILER_ID}" STREQUAL "Clang"' with it. This makes it possible to add more GCC compatible compilers in just one place.
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.
- Using USE_WINDOWS_DWORD on other platforms can cause problems.
Merge branch 'edward-san-cmake_gcc_compatible'
Merge branch 'gcc_aggressive_optimization' of github.com:edward-san/zdoom into edward-san-gcc_agressive_optimization
- Fixed edward-san's typo.
- Cleared a warning.
Use byte swapping functions from <libkern/OSByteOrder.h> on OS X

Remove inclusion of Core Foundation headers to avoid type conflicts with LZMA SDK.
Use correct 'true' keyword
Fix incorrect actor flag handling on big endian platforms
Merge pull request #78 from alexey-lysiuk/fix_osx_build

Fix OS X build
- fixed: transferring a translation to a missile needs to check if the missile was spawned successfully.
Merge remote-tracking branch 'zdoom/master' into openal
Replace another std::vector with a TArray
- fixed: When the 3D floor init code was updated 5 years ago for Vavoom's latest changes to its 3D-floor implementation it accidentally set the 3D-floor's alpha as its desaturation.
- this needed more fixes...
- Miscellaneous CMakeLists.txt fixes.

- fixed a CMake warning about uninitialized use of the variable CROSS_EXPORTS in the tools subfolder when CMAKE_CROSSCOMPILING is off;
- fixed a variable typo: CMAKE_CURRENTY_BINARY_DIR instead of CMAKE_CURRENT_BINARY_DIR;
- in src/CMakeLists.txt, fixed a missing merge of a portion of code from maint branch to master.
Merge remote-tracking branch 'zdoom/master' into openal
- fixed compilation with VC++2005 solution.

hu_stuff.h defined some callbacks for qsort without STACK_ARGS which causes problems with this solution's Release setting which uses __fastcall calling convention.
Merge branch 'master' of https://github.com/rheit/zdoom