Hyperlink usability improvement

Current behaviour:
Left click causes navigation in both edit and view mode

After the change:
Same as current behaviour in view mode.
In edit mode, left click will just move the cursor to desired position. In order to navigate, user need to hold control key and then click
Hook up the HyperlinkClickHandler with ODFViewerPlugin
Merge pull request #269 from kevinlli/hyperlinkImprovement

Hyperlink usability improvement