General housekeeping and cleanup. Move static declarations and

data definitions from .h files into corresponding .c files.
Blame zr for this since he's the one who pointed out that our
bpy headers were a mish-mash of stuff that belonged in the .c files!

In a nutshell, the headers should contain the declarations necessary
to use a module or class.  The implementation files ( .c in this case )
should contain statements that allocate storage ( definitions in
the C sense ) and executable code.

When used at file scope, the keyword 'static' means "don't tell
anyone else about this".  Since headers describe a public
interface, static declarations and definitions belong in the
implementation files.

The net result of all this is that after stuff has moved out
into the .c files, the .h files are empty or mostly empty.
I didn't delete them since there seem to be some public
declarations and because I did not want to cause too much
disruption at one time. Time enough for that later!