GUI transparency and mouse events

These changes add transparency option for GUI views, it makes screen quads render with alpha blend and adds on option to enable this transparency on WebViews (off by default)
The property for this is

    &WebGUIView
    >transparent=1b

This also makes mouseMove events take 4 parameters instead of the original 2, absolute position (normalized 0..1) and delta position (unchanged).
all mouse inject events return bool of status (clicked or not).