Erlang

Preliminary erlang support, no test suite yet.

Also, I tweaked some of my other runners and added documentation, however that stuff is not really related to erlang (given that we have a little backlog of pull requests, I figured I'd just put this stuff in the same branch)
In the case of solution only, it doesn't bother to compile the solution code, it just executes it directly in the REPL.

The setup code, however, needs to be compiled in order to be accessed.  One of the tests in the test suite checks this...