An object in Red Pixel II is anything that performs an action
(i.e. can have a script attached).  They are stored partly in the
`object_t' struct in C, and partly in Lua.

The bits that are in C are there to keep the rendering loop happy,
such as the object position, image, light sources, etc.

The rest is stored inside Lua tables, which means they are feel to
take advantage of untyped variables, associative arrays, better string
handling, etc.

See also `api.txt'.
