Document bhkRigidBody Unknown 7 Shorts defaults for Skyrim.

Add more Skyrim materials.

Add extra Skyrim body slots used by modders.

Skyrim material updates.

Niflib and pyffi cannot have same attribute with different types, so rename SkyrimHavokMaterial attributes.

Flag Mopp Data Size and Has Triangles as calculated (for niflib, see skyfox's niflib pull request #2).

Clean up the history, fix various bugs, unify xml for nifskope/niflib/pyffi.

Skyrim fix for BSPSysHavokUpdateModifier (see meshes/effects/dragoncrash/fxdragoncrashfurrow01.nif).

Patches from the pyffi branch required to get us back on a single xml.

Added ulittle32 type to enforce little endian regardless of specified byte order, updated nif header to use it.

NiGeometryData: Updated to enable data to be stored in a version independent way (required for pyffi).

Mark NiSkinPartition.num_triangles as a calculated field (this is needed as a first step to fix a bug niflib).

Partial revert of 054b932e as it broke Civ4 (see for instance art/structures/cities/all_city_lot_4x4.nif).

Someone who knows what that commit was about may want to revisit it.