Added word count
Implement method to get text content in DOM tree

Based on jQuery's implementation.
https://github.com/jquery/jquery/blob/bcca4f0/external/sizzle/dist/sizzle.js#L915

This is actually pretty fast, and should be efficient enough.
Use rendered HTML for word count
Base character counts off rendered HTML
Switch wordCount to NSPopUpButton
Fade wordCount when cursor is intersecting
Start with last used MPWordCountType
Disable word count alpha
Implement padding by resizing scrollview
Cleanup and correction

General code cleanup.
Word count text formatting is now handled by JJPluralForm so that they
can be localised correctly in the future.
Add license for JJPluralForm
Merge branch 'word-count-experimental'

Conflicts:
	MacDown/Code/Document/MPDocument.m
Add Joseph Stevens (@Mowsh) as contributor