Polymorphism is liek so 1337

Much more work has gone into the plugin. However, this time, I'm
focusing more on doing more work with less code. In light of that, the
temporary DateLexer class has replaced TimeLexer and has thus been
deleted.

TargetLexer has been rewritten entirely to use zeroes and ones to
determine values. It now supports stacked parentheses.

The inspect and missing commands are essentially finished - they just
need to be tested.

CommandProcessing will now automatically handle NumberFormatExceptions
so we don't need ugly try-catch blocks *everywhere*. We can use
e.getMessage().substring(19, e.getMessage().length() - 1) to get the
violating string.

 Tracker now supports a new MaterialDatabase class which handles
material names and matching.

I still need to finish EntityLexer and WorldLexer (the latter of which
may be scrapped and incorporated into LocationLexer).

SLOC: 7781.