Renamed the test files so that their name gives a hint as to what it is
that they are testing, without having to open the file

Pattern guards allow you to say that a particular pair should only be
replaced when the input matches a particular regular expression.

It is tied to the 'G' or 'Guard' control on the pair header, and is one
of the 3 or so major features I want to implement before a 1.0 release

As an aside, the other two features I want to add are:

Multibody Support
=================
This will allow a pair to replace to a few different things, based on
various conditions (the two main ones I want are some sort of cyclic
behavior, and some sort of guards for these)

Sub-application
================
Allow the application of a stage to the result of applying a pair/parts
of applying a pair. This will likely entail several sub-features such
as:

Named Stages
------------
A named stage is a collection of pairs that isn't applied by default,
but is instead used for convenient grouping of related pages together.

Custom Replacement
------------------
Instead of using replaceAll, I'll probably go for something using
appendReplacement etc. on Matcher and roll some sort of custom thing, so
as to provide for a convenient syntax for anything special I want to do
while running the replacement.

I'll also want to add some documentation, in addition to maybe doing
some restructuring to make how things are laid out more obvious.