py: Add 'static' to inline function MP_BOOL; remove category_t.

Small fixes to get it compiling with ARMCC.  I have no idea why
category_t was in the enum definition for qstrs...
py: Improve inline assembler; improve compiler constant folding.
Merge branch 'master' of github.com:micropython/micropython
tests: Add some bytecode tests.
py: Make all LOAD_FAST ops check for unbound local.

This is necessary to catch all cases where locals are referenced before
assignment.  We still keep the _0, _1, _2 versions of LOAD_FAST to help
reduced the byte code size in RAM.

Addresses issue #457.