Fix incorrect colors when packing C8 images with RGB5A3 palettes

Fix 1-bone models having no vert positions or normals

Reduce number of shape packets in SHP1 section

This significantly reduces the filesize of repacked SHP1 sections.

In order for this to work without making the model look terribly
corrupted ingame, several bugs were fixed. This includes bugs with how
the number of weight matrices per packet were calculated, and how
tristrips that exceeded the maximum number of matrices were being split
up.

Handle removing duplicate materials to save filesize

Fix several bugs when encoding/decoding images with resolutions not a…

… multiple of their block size

Fix incorrect default inverse bind matrices used

Some original BDL/BMD files don't specify any inverse bind matrices.
Previously all zeroes were used for these, but now all ones are used
instead.

Remove unnecessary debugging print statements

Fix float rounding when writing vertex data

Instead of flooring the float, round it either up or down depending on
what's closer. This fixes UV coordinates losing precision when converted
to BMD.

Make error when a mesh has more than one material more helpful

Prevent unnecessary duplicate weights being stored