POLite software simulation

[m8pple]

This is an attempt to pick just the software simulator out of my previous mess.

I've modified it a bit to try to make it as isolated as possible:

• I moved it into a subdir of apps/POLite/util, so that it is clear it is not an application.
• All the simulation logic is in a namespace POLiteSWSim, which resides in PGraph.h.
• The "fake" POLite.h just pulls a small number of types into the global namespace.
• polite.mk is modified to add sim and sim-release targets (I think I did slightly more than that, but the diff
  is not too bad I hope).

Apart from that, I also tried to make testing a bit clearer:

• New test script test_polite_sw_sim.sh which tries to compile all the apps, and then run a sub-set
  which don't need input files.
• Updated the description of the readme.md to add a final Simulation. note to the POLite section of
  the readme.
• Added a new appendix to the readme to talk about testing.

Unfortunately the actual simulation code in PGraph is still a giant blob, but I hope it is clear that it is additive
and shouldn't affect other parts of the repo, and at least there is testing there to show that it works.

I'd like to add more general testing in a separate pull, but kept it out of this one to minimise
the size of the patch.

[mn416]

Thanks @m8pple, I've made some tweaks to the docs. I'm on holiday this week, so will aim to merge early next week after I've had chance to try it!

[mn416]

HI @m8pple, this target was/is useful for running POLite apps on top of the hardware (Bluesim) simulator. Would be nice if this still works. I don't mind this target is renamed (as it clashes with the new sim target for software simulation), but we probably don't want to remove it.

[mn416]

@m8pple Very nice, it works for me, but please see the above comment about the hardware simulation target in the POLite Makefile before we can merge.

[mn416]

@m8pple, I've added back the POLite target for hardware simulation, renamed from sim to hwsim to avoid the clash. Will merge soon, unless you have any final comments.

[m8pple]

Thanks.

I think I just deleted the sim target as a side-effect without thinking about it.