Fixed crash on attempt to load corrupted data file

Instance of FileReader is no longer destructed when header of data file is valid but complete loading of file fails
Loading of truncated .zip file is the simplest test case
Added simple check for unsupported compression method in .7z files
Added support for LZMA2 compression method in .7z archives

Updated LZMA SDK to version 9.20
http://www.7-zip.org/sdk.html
http://downloads.sourceforge.net/sevenzip/lzma920.tar.bz2
- added constants for sound channels 5-7.
Fixed file list in VS2005 project of LZMA library
Fixed compilation with updated LZMA library using Visual Studio
Merge branch 'master' of https://github.com/rheit/zdoom into lzma2
Merge branch 'master' of https://github.com/rheit/zdoom
Merge branch 'master' into GLEW_VERSION
- start of attribute buffer implementation, so far used for the parameter buffer indices for glowing walls, dynamic lights and texture matrices.