Phase 1: Making the composite hardware abstraction layer (chal) explicit.

Goal: move all platform specific code from hijack.c and kernel/*.c
into kernel/include/chal.h (prototypes), platform/include/chal_plat.h
(static inline functions), and platform/linux/module/pgtbl.c (and
others, for globally visible functions).

Moved all page table specific code to pgtbl.c in hijack.  Started
moving functions into chal.h and changing their names at all call
points.
Phase 2: finished chal-ing page tables, address translation, and memory allocation

Nothing fancy here...just refactoring.
More chal migrations
Print component doesn't use the argument region any more.
merge conflict resolved
debugged some argument region issues
cosmetic refactoring