* put stdin into nonblocking mode, retry on short write to stdout #78
* wrap getc_blocking() around a poll #78
* get CCCflag from terminfo. stop clearing the screen in render/startup
* implement ncplane_at_cursor() #76
* ncplane_at_cursor() unit test for simples #76
* PlaneAtCursorComplex unit test #76
* PlaneAtCursorInsane() unit test #76
* nplane_at_cursor: return number of bytes, not just 0/-1
* uniblock-demo: add a bunch of pages from Unicode 12
* demo: make -d delay multiplier a float
* egcpool: check offset against poolsize in check_validity()
* notcurses_init(): set smkx/rmkx to NULL with pass_through_esc
* PlaneAtCursorAttrs unit test #76
* add ncplane_styles() accessor
* sliding: bounding box around puzzle
* slider: make moves, deleting planes #61
* implement z-index move functions
* demo: allow demos to be chosen via command-line option
* allow default bg/fg to be explicitly chosen
* ncplane_resize() unit test #64
* useful links
* slider: use random colors
* use find_above() in ncplace_destroy()
* ncplane_resize() work #64
