Started cleanup of VHDL.hs and some builtin funcs now expect CoreBndrs instead of...

Started cleanup of VHDL.hs and some builtin funcs now expect CoreBndrs instead of VHDLIds

VHDL.hs now only deals with functions that use the VHDLState Monad
All the other (helper) functions are now moved to VHDLTools.hs

Commented functions in VHDL.hs that relied on Flatfunctions. They
are ready for either removal, or should be updated to use Core
types.