Pixelbuf support

[rhooper]

This MR adds support for _pixelbuf.

Notable is that this means .buf is gone. The way _pixelbuf works now means there is no .buf property. In theory we can emulate that with a @Property.

[tannewt]

Thanks for adding this! I'd like to wait to merge until 5.x is stable because 4.x crashes.

[dunkmann00]

Is this good to be merged now that CP is at 5.0?

[dunkmann00]

@kattni Any plans for when this can be merged back in?

[tannewt]

@dunkmann00 We don't have any immediate plans though we should be able to do it. Maybe we can once @rhooper dusts off the PR? I may have a variant somewhere here too. It'd be good if it fell back to PyPixelBuf based on the CircuitPython major version instead of whether _pixelbuf is available.

[dunkmann00]

@tannewt I'd love to help out with this if I could? I'm not sure how I would go about that though. Should I fork @rhooper's version and just fix the conflicts/fallback code and make sure it plays well with CP 5.0?

[tannewt]

@dunkmann00 That would be awesome! You can create your own branch based on his code and do a separate PR.

I also have these changes I made: master...tannewt:update_for_pixelbuf

The main thing is to ensure it works well in 5.x and uses pypixelbuf in 4.x rather than crashing.

Thanks!