- search for alternative virtual address regions upwards, starting from
the given start address, in the 'l4re_rm_attach()' and
'Region_manager::reserve_range()' functions
- don't treat memory locations above 0x80000000 in l4linux's virtual
address space as device memory
- align the start address of the vmalloc area according to the assumption
in 'devicemaps_init()'
Fixes#414.