QDENGINE: Add support for rgba8888 pixel format

[ormanbai123]

This PR attempts to bring rgba8888 pixel format to the engine. Changes have been made to every drawing function, except for putSprMask and putSprMask_rot methods. So far during playtesting I haven't seen these methods being called, so I put STUBs to them for the moment.

[ccawley2011]

Would it be possible to make this configurable at run-time, so that it still works with more backends?

[ormanbai123]

Would it be possible to make this configurable at run-time, so that it still works with more backends?

Yes, I think is possible to do so.

Then during engine initialization I should check if backend supports rgba8888 with with OSystem::getSupportedFormats(). If yes, then use that format, otherwise use rgb565 as before. Do you mean something like that?

[sev-]

The I recommend adding a GUIO "run in 16bpp" and a debugflag "16bpp", so it is possible to switch it from the command line, and use it.

Question, your shveik shadowing fix, will it also work for 565?

[ormanbai123]

Question, your shveik shadowing fix, will it also work for 565?

Yes. In fact, it fixes the 565 version. 8888 was already working correctly from the first commit.

[sev-]

Thank you!