Learning a language the human way

Some machine learning algorithms (all the ones I'm familiar with) learn
language arbitrarily (this word probably means "house", that verb might go over
there, etc. etc.) which leads to fairly daft grammars. Human languages do not
seem to work this way because there are some constraints on syntactic
variability. In other words, the human language faculty never produces an
arbitrary syntax.

This commit introduces a method of learning a language the same way that
children seem to do, by my undertanding of the Chomskyan linguistics and the
Principles and Parameters theory. This is mostly implemented under the
languages/pp and imports/pp directories.

If you want to know more about this fascinating business you could read
Mark Baker's book called the Atoms of Language.