G364 video adapter enhancement

G364 video adapter enhancement

This patch improves G364 video card emulation (used in MIPS Magnum machine):
- Use memory dirty tracking to not refresh whole screen each time
- Use macros for debugging messages
- Add support for hardware cursor
- Handle Y-panning
- Raise irq at each screen redraw
- Support retrieving of some registers
- Add load/save support

The emulation has been tested in Linux 2.1 and Windows NT 3.5, in
640x480, 800x600, 1024x768 and 1280x1024 resolutions.

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6356 c046a42c-6fe2-441c-8c8c-71466251a162