This previously had logic in it that was very wrong and could lead to
memory corruption or a failure to properly mark data as freed.

Also introduces a bunch of tests for various edge case behavior.

This allows them to be packed more efficiently, rather than always
starting at a bitmap start.

This commit changes a LOT of areas of the code to use decl literals
instead of redundantly referring to the type.

These changes were mostly driven by some regex searches and then manual
adjustment on a case-by-case basis.

I almost certainly missed quite a few places where decl literals could
be used, but this is a good first step in converting things, and other
instances can be addressed when they're discovered.

I tested GLFW+Metal and building the framework on macOS and tested a GTK
build on Linux, so I'm 99% sure I didn't introduce any syntax errors or
other problems with this. (fingers crossed)