CELL_ALPHA_OPAQUE et al were defined as 0..3, meaning
CELL_ALPHA_SHIFT had to be used to compare them to their
channel representations. Instead, define them in said
representation outright, eliminating the need to shift while
retaining arithmetic properties, and zero initialization for
CELL_ALPHA_OPAQUE. Eliminate CELL_ALPHA_SHIFT #738.
Whip the ol' llama's ass (fix ncvisual rotation)
* notcurses: flush cursor change requests #673
* rotator: verify ncplane_rgba and ncblit_rgba
* ncblit: rename, accept ncblitter_e #674
* rotator: render from rgba
* rotator: get to rotation
* rotator: add a pi/4 turn at the end
* normal: reuse incoming plane for rendering #672
* rotator poc: rotate a fullplane gradient #672
* normal demo: place visual correctly
* rotator: verify ncplane_rgba and ncblit_rgba
* ncblit: rename, accept ncblitter_e #674
* rotator: render from rgba
* rotator: add a pi/4 turn at the end
* normal: reuse incoming plane for rendering #672
* rotator poc: rotate a fullplane gradient #672
* normal demo: place visual correctly
* rotator poc: throw some red into gradient
* rotator poc: done #662
* oiio: ncvisual_resize() needs set ibuf pointer #662
* normal: only need erase at top of loop
* visual poc: shorter delay
* normal demo: center rendered visual
* comment ncvisual_resize() call
* ncvisual_rotate: call ncvisual_details_seed()
* ffmpeg ncvisual: fix rotation #662
Replace the singly-linked z-axis with a doubly-linked list,
and reimplement all z-axis moves as O(1) functions.
Eliminate ncplane_move_{above/below}_unsafe(), as there are no
longer unsafe moves.
Unify ffmpeg/oiio/null implementations, where possible. This effectively
required placing all three in the same file, which meant they're all now
C++. Update FFmpeg implemenation to be C++-usable. Implement
ncvisual_rotate_cw() and ncvisual_rotate_ccw() #515. Move most of tetris
over to Visual from Plane #558. Add bgra_to_rgba(), necessary for
creating ncvisual from BGRA memory. Implement ncvisual_from_rgba()
and ncvisual_from_bgra() #557. Add unit tests on ncvisual rotation.
