why:
it was convenient to have relocatable source modules when writing the
vm interface wrappers. this patch moves it back to the standard.
also:
there are no deep links into the vm folder anymore which leaves some
room for manoeuvring inside
why:
the nvm_ prefix was used inside the vm folder to hide them temporarily
from the outside world while writing export wrappers. now all
functionality is accessed via vm_*, rather than vm/* imports.
todo:
at a later stage the import headers of the vm modules need to get fixed
to meet style guide standards (as jacek kindly pointed out.)