code cleanup, remove OO_ALSO_USE_OLD_FIRM_PROPERTIES variant
remove pointless config.h
Introduce VptrIsSet node

This node is used to mark points in the program where an objects vptr is
fully initialized. The operation is a NOP and will be removed when
lowering OO constructs. The idea is that the node conveys information useful
for optimizations.
Add proof of concept InstanceOf(VptrIsSet()) optimization

We can immediately evaluate instanceofs when we can still see the object
allocation.
(This is a proof of concept as its only 1 of many usefull local
optimizations)