JSCS: fixes for missing errors.
Removed JSCS comments surpressing errors which are not thrown in the latest JSCS version.
Updated .jscsrc according to https://github.com/ckeditor/ckeditor-boilerplate/issues/2.
JSCS fixes after recent .jscsrc update.
Merge branch 'master' into major

Conflicts:
	core/editable.js
	tests/core/tools.js
	tests/plugins/forms/textarea.js
Tests: New tests for HTML and text insertion into not focused editor.
Editor must be focused before retrieving range and before transforming text to HTML what requires context.
Merge branch 't/12726' into major
Added dev/builder/release to directories ignored by JSCS ans JSHint.
Merge branch 'master' into major
Improved element#add/remove/hasClass methods.
Fixed incorrect addClass usage.
API docs: Minor improvement.
Reverted incorrect change made in #3679.
Code refactoring: Reused the hasClass code which does not create regexp patterns for every class.
Fixed more incorrect addClass usage.
Tests: Improved test cases names.
Tests: Added missing tests for element.hasClass.
Changelog entry.
Merge branch 't/10903b' into major