Memory editor should mark N/A addresses

When the user tries to access memory addresses which are not mapped in the application, the memory editor shows the entire range as zeros. This often confuses the users, which think this memory is valid and has zeros when in fact it is invalid.

It would be better to mark these areas with NA (or another notation, preferably with some background color) instead of zeros.

Another improvement to the memory editor can be to mark/skip unmapped regions. The mapped sections can be retrieved (at least on GDB) from maint info sections, which can be updated on each step (if a memory editor is open).

This can help figure out if a pointer references an invalid address, and also improve searching in memory.