New Structured Editor for Template files

Here is a list of what is implemented and some known bugs.

###### Features
* Feature parity with the old template editor.  
  * Scala as-you-type error reporting  
  * Scala auto indentation
  * Scala completion proposals  
  * Scala hyperlinking  
  * Scala/HTML syntax highlighting  
  * Scala text hovering  
* New HTML goodies:  
  * Improved HTML syntax highlighting  
  * Javascript and CSS syntax highlighting  
  * HTML completion proposals (tags and attribute values)  
  * HTML text hovering  
  * Matching bracket and matching tag navigation  
  * Highlighting of the cursor's current opening and closing tags.
  * Anchor tag hyperlinking  
  * Code folding  
  * Content outline and Quick outlines

###### Known Issues
* Import error markers occur on the incorrect line.  
* Previous existing parser problems inherited by using the Play2 tokenizer  
  * When typing scala code, a trailing '.' is interpreted as HTML, thus giving html completion proposals instead of scala completion proposals (if triggered by completion proposal shortcut, since html completion proposals don't use the '.' as an activating character).
  * Noticeable speed issues on files even as small as a hundred lines or so.  

The old template editor has been left in place, but is no longer the default. You must explicitly right-click, and select Open With -> Template Editor. 

Finally, please let me know if/how I should clean up and combine some commits. Some of the earlier commits in particular I made just to get the code I had written backed up on the github servers, so they are not particularly informative (nor is the associated code in the cleanest state).