(core+) native cursor and agp dirty drawing fixes

Fixes to how the cursor support script handles native
modes with additional support for absolute coordinates.

This is also the first push that shifts the world-rt
drawing responsibility to the platform driver in order
to be able to account for multi- display mapping and
preferences.

Furthermore, native mouse forced updates when uncesseray,
while pending transformations did not correctly apply to
rendertarget dirty state.

Lastly, erase pass used the wrong coordinates. Now, mouse
drawing swaps between last visible and currently visible
coordinates in order to correctly redraw only the dirty
area under the cursor.
(platform) build/render order fixes