Undo/redo initial implementation.
Browserify `object-history` in PhantomJS tests, as well.
Small typo fix.
`$ grunt clean:lib` task.
`getCurrentState` doesn't leave selection boundaries behind.
Add undo/redo tests for list actions and selection restoration.
Undo/Redo covers all toolbar actions. Tests included.

There are no tests for dialog actions link, image, paste and table.
JSHint pleased with Undo/Redo tests.
Add expectancy for Undo/Redo tests.
Documented that some dialog actions' `registerChange` don't got tests.
Add `undoRedo.reset`.
Delete `win` and `doc` from `savedSelection` in `getCurrentState`.
Fix UndoRedo test.
Test selection in UndoRedo in a more cross-browser way.
`getCurrentState` uses `rangy.isSelectionValid`.
Add sourcemaps (debug option) to browserified things.
`object-history` to `v2.0.0`.
Add `es5-shim` and sham to tests and examples.
Remove trailing comma.
`registerChange` only if list action made changes.