`WymClassBlink` proof-of-concept.
`WymClassFirefox` renamed to `WymClassGecko`.
`WymClassExplorer` renamed to `WymClassTrident`.
Remove `WymClassOpera` because it is using Blink.
For now, use the WebKit editor class for Blink.
Added changelog entries that were not added in their respective merges.
Merge pull request #524 from mightyiam/changelog_stuff

Missing changelog entries
We don't need CHANGELOG entries for test-specific changes
Merge branch 'wym_class_blink' of https://github.com/mightyiam/wymeditor into mightyiam-wym_class_blink

Conflicts:
	src/wymeditor/editor/gecko.js
	src/wymeditor/editor/webkit.js
Merge branch 'mightyiam-wym_class_blink'
Using `WYMeditor.NODE.TEXT` instead of `3` in some places.
Code comment typo.
'Selection Setting and Getting' documentation fixes.
Merge branch 'master' into selection_api_bug