Is the VDC framebuffer always un-ready after a control register write?

[lavignes]

We always reset the ready state of the framebuffer when parameters change.

possum/emu/src/vdc/mod.rs

Line 373 in c6281ea

self.framebuffer_ready = false;

Not sure what happens on a real device but it is likely that changes to the control registers would apply mid-frame. So we should remove this to allow funky raster effects :)