VCL: Remove unused and deprecated debug check function

Change-Id: I3fcf630b8a0ef5be0d98ddc11a746e07885bae53
VCL: ImpObjStack replaced with std::stack

ImpObjStack uses it's own home-grown stack and stack functions. There
is a function that unwinds the stack, but really it would be better if
we used std::set. In fact, this is better, because the name ImpObjStack
is really not terribly descriptive. I've replaced it with a stack of
OutDevState objects.

Change-Id: I87bdd4340ad77b7ffd9ff176fa5a9ffeac8b8666
VCL: Move OutputDevice map structures to own VCL header file

Change-Id: Ifbaa51018d47fde72be80d5d1870fdda214db320