Added implementation of EM planning
Refactored grammar compression code. Added a comment describing what annotateRequested does, and why it does it.
Fixed bug in sampler
Changed planner to use log probabilities
Fixed bug caused by not rerunning type inference on new library procedures
Planning test case implemented. Currently fails tests.
Fixed bug in the planner. Planner seems to now working; can solve the number task.
Added test polynomial regression test case for planner. Seems to do very well, even on small frontiers/plan lengths/mcmc runs
Added limit to the number of evaluation steps that are allowed
Added parser for expressions, sanity checker for substitutions, saving/loading grammars to files, and timeout for expression evaluation. Planner and EM now do not get tripped up by programs that have space leaks, and seem to work.