Improving maps output.

Maps output now displays fault address location more intelligently.  If
the fault is not in a mapped region, it now shows where that address is
with respect to the other maps.

In addition, the size of the map is now printed as part of the output.

Also, crasher now supports an "mmap" option which mmaps/munmaps a region
of memory and then attempts to access it, causing a fault address in
between mapped regions that can be used to test that new part of the
maps output.

Change-Id: Ia5e1926802bdfcbbdb7857e3631ddf395ae0c5b8