#1 Add byteswapping for old saved games

[Joshua Root]

This patch adds detection of saved games that aren't in the native endianness, and byteswapping to allow loading them. I've used it to load several saves created by the old PPC Mac version and haven't noticed anything obviously wrong so far. There is one possible alignment/padding issue as noted in the comments; I don't suppose you know what settings were used to build the old app? If there used to be padding but now isn't, or vice versa, part of some of the structs will have to be shifted 2 bytes forward or back. Ugh.

[Joshua Root]