CHANGES:

1. Added the TerminalSequences class.
2. Added storing and loading features for PCFG.
3. Added the ArgumentProcessor class.
4. Fixed bugs in handling unknown words.
5. Edited the main file to actually do work.
6. Added appropriate tests.

TODO:

1. Remove the dependence on ASSERT in util.h.
2. Find a better solution for handling unknown words: need lexical info, not -1.
3. Serialize PCFG instead of writing in string format.
4. Make log probabilities.