selectedContainer documentation and code comment fix.
`editor.hasSelection`
testWym general testing utility.
Make jshint happy.
Use a non-empty document in the hasSelection tests.
editor.getSelectedNodes()
Use editor.getSelectedNodes here and there.
Merge branch 'master' into selectedContainer_fix

Conflicts:
	src/test/unit/test.js
	src/test/unit/utils.js
`editor.deselect()`
Test `deselect()`.
Some tests for `getSelectedNodes`. Some fail in IE8.
editor.setSingleSelectionRange not public. Prepend underscore to that.
editor.setSingleSelectionRange not public. Prepend underscore to that.
Make editor.getSelectedNodes private!
Merge branch 'selectedContainer_fix' of github.com:wymeditor/wymeditor into selectedContainer_fix
Fix typo in changelog.
Selection tests got their own file.
Use correct assertion functions in selection tests.
`_getSelectedNodes`: removed failing tests and added passing tests.
Merge pull request #613 from wymeditor/selectedContainer_fix

Fix `editor.selectedContainer`