Implementing domain maps

[hkaiser]

• adding default rectangular domain map
• adding domain support to Array
• adding heat examples (hand translated from heat.chpl and heat_ghost.chpl)
• adding write()/writeln()
• flyby: handle CHPL_ environment variable during startup
• adding registerModule utility API

[hkaiser]

@ct-clmsn I think this is ready to go as is. All tests are passing again as well.