Fix multiple inheritance in mem tracking by dynamic casting pointers to void*

[naalit]

Fixes #476 (hopefully, unless I missed something) by inserting dynamic_cast<void*>() everywhere a pointer of non-void* type is passed to the pointer tracker within Ptr.

[mercere99]

This is an interesting fix, and I think it should work cleanly. My instinct was to keep track of all of the conversions and offsets, but that would be a ton of additional bookkeeping. I believe that this fix will do the right job.

[mercere99]

Looks like tests are failing. Looking more into dynamic_cast, it apparently ONLY works with polymorphic types, so it won't easily solve the problem here. We need to wrap all of the conversions in some type traits tests to make sure they are polymorphic before we try to resolve them. I'll look into it some more (unless you have time to first) and try to get this resolved.