JBIDE-16687 provide access to palette entries via content assist
JBIDE-17154 HTML5 Version Popup Window wrong placement

Updated in order to take into account palette scroll
JBIDE-17156 Palette wizards of HTML category should not have 'Add js/css' checkbox
Inheritance of Palette wizard is changed so that super class has only
functionalyty common for all widgets, while specific of jQuery and HTML
is moved to subclasses.
Updated IVisual interfaces for vpv compatibility