Merge pull request #86 from interwq/master

PPOS  update
Added invocation and return code!  This includes thread management,
pgtbl switching, and invocation stack management.

Lots of FIXMEs so please don't ignore those.  Lots of functions
(e.g. pgtbl_update) need to be updated to reflect the real machine
(i.e. write to cr3).
Changing cos_loader.
Updated scripts. The entire system still works under current
design. Going to change a lot next!