64 bit compatibility

```
IntToHex and Format currently generate 8-character renderings for pointers. 
Make that 16 characters under 64 bit.

Also, Pointers are cast to Integer, which truncates the 32 high bits. Instead, 
use IntPtr instead (or NativeInt if you must).


```

Original issue reported on code.google.com by `pvanlogc...@gmail.com` on 5 Jul 2013 at 2:48
