Fix upper body of character.

Start effort on rigging right arm of character.

The SDL.h include is only valid for macOS because of memset_pattern4, on
Windows it is not required.

The character and weapon sprites have been updated.

Simplify design of grenade launcher in Paragon.

Add belt to skirt..

Add shading for 1st character.

Add coloring, fix head for 1st character.

Split head components into multiple layers.

Update Paragon details.

Define other playable characters.

Balance weapon stats.

Improve character sprites.

Add second character.

Improve sprites.

Add joints to character sprite.

Include characters sprites.

Add some missing parts.

Use common terms for geometry groups.

The sprites are now loaded using a utility function in IZ_video.