mmio: provide bits method for bitsets

ref #1006
Clarify comment
mmio: provide set and get method for bitsets

ref #1006
hw & arm: simplify TLB permission bits via bitsets

ref #1006
hw & arm: simplify TLB descriptor-type bits

ref #1006
hw & arm_v7: clean up TLB driver

ref #1006
hw & arm_v6: clean up TLB driver

ref #1006
hw & arm: declare every mapping as MP shared

ref #1006
hw: kernel initialization in extra function

ref #1006
hw: fix assembly alignments

ref #1006
hw & arm: clean up core CRT0

ref #1006
hw_arndale: idle threads on secondary processors

fix #1006
hw: move Thread::_processor to Execution_context

ref #1078
hw: move handle_interrupt to Execution_context

ref #1078
hw: make _processor private to Execution_context

ref #1078
hw: rename handle_exception() in exception()

fix #1078
hw: rename core/cpu/ in core/processor_driver/

ref #1083
hw: adjust defines in core/processor_driver/

ref #1083
hw: rename cpu.h in processor_driver.h

ref #1083
hw: adjust defines in processor_driver.h

ref #1083