Don't re-order non-ODF children when merging paragraphs

Child order of non-ODF nodes should be preserved when merging
paragraphs.
Merge pull request #361 from peitschie/remove-text-fix

Don't re-order non-ODF children when merging paragraphs
Add tooltip support for hyperlink
Refactor HyperlinkClickHandler.js

* moved related event bindings from SessionController.js to HyperlinkClickHandler.js so bindings will be updated everytime the modifier is changed
* removed HyperlinkClickHandler.Modifier and use the KeyboardHandler.Modifier instead
Change the word "Command" to ⌘ in the tooltip