Multiple editor viewports
Merge remote-tracking branch 'remotes/friesencr/editor-viewports'
Fix multiple view raycast. Fix nearclip/farclip/fov editing. Fix camera look (right mouse) when switching between views. Cleanup UI / camera initialization order. Save viewport setup to editor config file.
Set forced max. priority for the Menu/DropDownList popup so that it's more reliably displayed in front.