Started implementing BTX in java

It is untested, simple, and gives no positives over XML, but it's a
start. The next step is to implement a reader based off of iteratively
reading the file, rather than reading it all at once into memory.
Implemented an iterative version of the API for BTX

Made an iterative version of parsing the BTX format. Acts similarly as
an XML pull parser.
Bugfix

I should really get some unit tests up
Slight API change

Moved the Pull Parser functionality to a new type rather than in the
normal "File" type
Added methods to output data in BTX
Accidentally didn't commit this
Simplification of BTXParser implementation

Used a linked list for the stack rather than an array list.
Added a way to create BTX documents without creating them in memory

Created an object that works in the opposite manner of the BTXParser. It
may not actually work yet; I'm adding test cases next.
Bugfix and simple test file

I'm going to change the BTX file format soon so that things can be a
little more flexible in the parser.