Remove "org.eclipse.angularjs.core.angularsource" content type

[angelozerr]

The content type "org.eclipse.angularjs.core.angularsource" is used to use a custom JFLex parser to create angular expression region. It work's great but there are some limitations :

• the JFlex parser was redefined only for HTML and not for JSP. So for JSP highlight cannot be done.
• HTML file must be opened with the specific AngularJS Editor which use LineStyleProviderForAngular to highlight angular expression. If you open the HTML file with WTP "HTML Editor", angular expression are not highlighted.

The highlighting can be done with semantic highlighting. It was done for JSP #80 So no need to build a custom DOM for Angular to detect region. Completions, Hover, Hyperlink for angular expression works too for JSP, so it will work too for HTML.

With semantic highlighting, we will able to support interpolation markeup #68