Added some boilerplate to the rendering system. It's now impossible to start new rendering cycle if the previous one hasn't finished yet.
Changed: OS name, GPU name and GZDB revision info are now added to the exception text and GZCrash.log.
Fixed, cosmetic: toolstrip separators visibility must be updated when resizing the main window.
Internal: removed Plug.DisplaySize, Plug.DisplayLocationAbs and Renderer.ViewportSize. The same data can be accessed from anywhere using General.Interface.Display.Size and General.Interface.Display.LocationAbs. Also Plug.DisplayLocationAbs returned incorrect coordinates...