Split UIElement::OnClick() to OnClickBegin() & OnClickEnd(), added global UIMouseClickEnd event, cleaned up Button & CheckBox click handling, based on Chris Friesen's work.
Fixed bug in FileSelector which would cause potentially any keypress to select a file.
Added missing icon for View3D UI element.


git-svn-id: http://urho3d.googlecode.com/svn/trunk@2484 3bd170d8-ddcf-f82c-f583-7a401ccf5608