No longer cursor insertion in SessionController.startEditing, fix cursor removal where missing
Fix incomplete destroy of SessionController
Add gui.EventManager.destroy()
Fix InputMethodEditor.destroy not unsubscribing from all events
Merge pull request #387 from kossebau/fixStartEndEditing

Unbreak Editor loading a new document with same canvas, but new session & controllers
Clear the stylesheets in OdfCanvas inside refreshOdf
Merge pull request #386 from kossebau/cleanStylesOnRefreshOdf

Clear the stylesheets in OdfCanvas inside refreshOdf
Split the word boundary filter out of SelectionController

Primary intent is to reduce the size of the selection controller class,
in preparation for some additional fixes to aid word boundary detection
in non-english languages.
Rewrite move & select via word boundaries to use a step iterator
Rewrite range-based word boundary expansion to use step iterators
Cope with non-latin alphabets when searching for word boundaries

This has been sourced from http://apps.timwhitlock.info/js/regex, which
creates these sets using the cset JS library. The set includes all
punctuation components only.

Addresses issue #268
Reword variable names to improve code readability
Move WordBoundaryFilter to the ODF namespace to allow for wider reuse