MKID_BE relied on unspecified behavior of the C++ compiler,
and as such was always a bit unsafe. The new MKTAG macro
is slightly less elegant, but does no longer depend on the
behavior of the compiler.
Inspired by FFmpeg, which has an almost identical macro.
Bug #2812694: "CINE: Operation Stealth german crash". Our code
assumed that there exists only 256-color version which is not
the case for German version. Added code to store background
format. Old savegames are broken and could not be fixed.
Bumped savefile version.
svn-id: r49699
