minimized, css styling and made menu items behave as buttons with the @ prefix

* Changed css styling, to better cope with small menu widths.
* Added minimize parameter (true/false) which when enabled shows only
  a small square with the text [show] to open up the menu
* Added a new menu item text prefix @, which will make the text inserted
  displayed as a link and on click will show the menu's subtree
* added style attribute which behaves the same way as
  any html tag's style attribute.
example:
<sidebarmenu style="width: 100px;" minimized="true">
  MenuItem1
  +*SubMenuItem1
  -**@SubMenuItem1Of1
</sidebarmenu>

Change-Id: Ifae83a51e6a199b08480cb6ade6a94ac281345dc
Merge "minimized, css styling and made menu items behave as buttons with the @ prefix"