Import parent POM for standardization.

The parent POM file standardizes both build options and the versions of
various libraries. It also makes the build definition file much simpler
and easier to follow.
Add a utility object for working with files.

Working with files is one of the most common utility functions. This new
object `FileUtil` makes it very easy to work with streams of data at any
URI by sitting on top of Apache's Commons-VFS framework.
Include Logback as a test dependency.

Since these libraries do logging, they need some kind of logging
framework present whenever they are run. Test dependencies are a good
way to handle this kind of requirement, especially since this project
should really have some unit tests. (Although a lot of the code in this
project is too simple and difficult to test to be worth the effort.)
Don't inline `LexerUtil`'s `chars` method.

The compiler doesn't seem to allow inlining this method--possibly
because it's defined in a trait. This method is probably a little
complex for inlining anyway, so let's just let it be a normal method
call. Building the parser combinator is a relatively infrequent
operation anyway since they're expensive enough to require reuse.