Implement backup build order

[adamjford]

We need an alternate build order to switch to when our bunker build is not effective.

Probably marines/medics rush is fine. Check out the default zealot rush build for inspiration, as the default one is missing some stuff.

[xiasuke]

This bot uses the ualbertabot code and it might be useful to see other strategies it uses.

https://github.com/filipbober/scaiCode

[adamjford]

Issues discovered so far with the default Marine Rush build order:

• The search is really, really slow. Once the "opening book" is exhausted, the game reverts to default speed for quite a while until the search is complete. I haven't tried the default Zealot Rush to see if it's an issue there too.
• The medics don't appear to actually heal. They're too concerned with moving around to somewhere else, it appears.
• Once the results of the first search occurs, it takes a long time to perform another search again, but this time it only seems to result in a ton of SCVs being constructed.

[xiasuke]

Oh, so this is where this comment was ^

• Ok, as I said in my commit earlier, the search is somewhat fixed, the search doesn't take as long anymore, there are times where it takes a while but not as much.
• And as for the medics they are treated as marines (can be found in CombatSimulation.cpp)
• The ton of SCV's problem seem to be fixed for the most part now.