Completely de-coupled the *-matcher and *-mapper libraries.

 Earlier, the -matcher libraries used the -mapper libraries
 directly, to get results directly from the DOM, but now these two
 steps of the search has been permamently separated, so this is no
 longer necessary. The end result is that now the matcher library
 only needs a way to access the corpus, and nothing else.

 As part of this, I have removed all wrapper functions, that was
 placed on the -matcher layer, to wrap the -mapper layer.
 Now these are called directly on the -mapper layer.

 Furthermore, the matcher library is now completely mapper independent,
 so I can get rid of the separate ancestor and mapper-specific descendant
 classes.

 The library is still called dom-text-matcher, but now the
 name is just a legacy; it's not touching the DOM at all.