Re-introduce PtrToBVExpr the type system needs these
Garbage collect comments
Fix bug where PtrToBV was not used
Reverse garbage collection order
Move pointer generation

It might be that the use of pointers is only
detected during global array generation.
Remove redundant check and parentheses
Small style changes
Introduce SafePtrToBV and SafeBVToPtr
Align switch cases
Use SafePtrToBV and SafeBVToPtr

These are used everywhere, except for PtrToInt and
IntToPtr instructions.