AMIGAOS: Fix hardcoded version information

The AmigaOS version information still shows "ScummVM"
Merge pull request #1090 from raziel-/patch-1

AMIGAOS: Fix hardcoded version information
COMMON: Add the original Xbox to the list of platforms
MYST3: Add detection for the Xbox PAL version
MYST3: Look for wma sound files

Used by the Xbox version. Playing wma files is not supported for now
MYST3: Don't hardcode opcode indices
MYST3: Opcodes are slightly different of the xbox version
MYST3: Load the language archives for the xbox version
MYST3: Refactor subtitles handling to allow different kinds of subtitles
MYST3: Add support for the xbox movie based subtitles
MYST3: Refactor the variables system to allow remapping the ids
MYST3: Account for the variable mapping differences of the xbox version
COMMON: Add support for reading 64bits values from streams

Taken from xoreos
COMMON: Add getRevTab to FFT
AUDIO: Add the WMA decoder from xoreos

Credits go to DrMcCoy, clone2727 and the ffmpeg authors
Permission is granted by DrMcCoy and clone2727 relicense this
from GPLv3+ to GPLv2+.
MYST3: Plug the WMA decoder, to be used by the Xbox version