Added:
* Plane: gradient (`ncplane_gradient`)
* Plane: gradient_sized (`ncplane_gradient_sized`)
* NotCurses: drop_planes (`ncplane_drop_planes`)
* NcReel: constructor which takes `Plane&`
* Visual: constructors which take `Plane const*`, `Plane&` and `Plane const&`)
* ncpp_build: a nonsensical "demo" which exists purely to test whether
the C++ builds and does absolutely nothing interesting.
Broke:
* All exceptions throw temporary objects instead of allocated
instances. Less typing in `catch` :P (and more conventional)
Get rid of annoying empty line in notcurses-view (and ncvisuals at offsets in general)
Implement most of the Selector widget. Need to add styling and scrolling still. #166
Reenable ubuntu focal build
Subtitles! We decode them, and display them in notcurses-view. If ncvisual_simple_streamer() is provided an extra ncplane, it will use it to display subtitles. #95
We now build Python by default, as things are working much better.
ncplane_set_base() now takes channel, attrword, and EGC, so you can usually avoid having to set up and release a cell. ncplane_set_base_cell() takes over duty from ncplane_set_base() for ease of conversion.
notcurses-demo and notcurses-view now both accept a 0 for delay multiplier, meaning 'go as fast as you possibly can'. Very small multipliers (e.g. 0.00001) no longer cause floating point exceptions.
fading routines no longer cause floating point exceptions on very small timescales.
