Instead of having an ID allocator per object class use one global allocator for
all. Thereby artificial limitations for the different object types are
superfluent. Moreover, replace the base-hw specific id allocator implementation
with the generic Bit_allocator, which is also memory saving.
Ref #1443
* enables world-switch using ARM virtualization extensions
* split TrustZone and virtualization extensions hardly from platforms,
where it is not used
* extend 'Vm_session' interface to enable configuration of guest-physical memory
* introduce VM destruction syscall
* add virtual machine monitor for hw_arndale that emulates a simplified version
of ARM's Versatile Express Cortex A15 board for a Linux guest OS
Fixes#1405