changes to build configuration required for iridis
change to keep iridis installed gcc happy
changed KeyMap iterator to get it to build but tests fail
more work on this
Additional checks and print statements to help find bug
Complete overhaul of KeySet iterator implementation.

These changes where required for compatibility with the standard
library implementation on iridis.
Relaxed maxsumHarness requirements

Previously we required maxsum to do better than random on non-colourable graph.
We still report this, but no longer treat failure as an error.
made iterator constructor explict + extra comments
relunctantly reverting to std:map in PostOffice

Iridis standard library/gcc doesn't like it, unless in debug mode.
moved back to flat_map with typedefs (using gcc 4.6.1)

The previous problem seems to disappear with gcc 4.6.1 on iridis.
Added handy define to switch between implementations, but ultimately
reverted back to our faster flap_map dependencies once it was clear
that gcc 4.6.1 fixes the problem. Still not sure about the root cause
however.