Remove data that should be computed on the fly from the XML files outputed while unpacking a sprite!

[PsyCommando]

We don't want to let users handle those, as they're virtually useless to them, and not setting them correctly can mess up everything !

The ones that should be removed so far are :

• XOffsetBit5 / IsLastMFrameInGroup (Can be deducted from the ordering of the frames in the XML file)
• Is256Colors ( Can be deducted from image file's bit depth )

The others considered for removal are:

• Meta-Frame resolution ( Can be deducted from image file )

[PsyCommando]

Only the image resolution is left, and once the way resolution is stored in WAN sprite is better understood it will go away as well !

[PsyCommando]

A tradeoff was made with the image resolution. If a mismatch between the meta-frame and its corresponding image is detected, the meta-frame will be automatically fixed by the application. However, it will only work if the image's resolution is one of the valid resolution!:
8 x 8
16 x 16
32 x 32
64 x 64
16 x 8
8 x 16
32 x 8
8 x 32
32 x 16
16 x 32
64 x 32
32 x 64