Add the necessary input buffer, non-blocking reads, escape trie,
and unit tests to support extended keys, including arrow keys.
Update notcurses-input to print Unicode Control Glyphs instead of
a blank space for control chars.
This addresses an issue where callers of notcurses_getc_blocking()
wouldn't exit on SIGINT etc. until another keystroke was received.
The exit is now immediate, and the proper exit code is propagated.
Slider demo: paint chunks in a pattern, then shuffle them up #72
Right-to-left unit tests #66
Fix up damage to uniblock demo using cup explicit cursor move #66
* cell/ncplane: simplify box API (#97)
* widecolor: use new box api (#97)
* uniblock: use new box API #97
* intro: use new box api #97
* panelreel: use new box api
* boxdemo: use new box API #97
* sliding: use new box API #97
* maxcolor: use new box api #97
* factor out notcurses_channel_prep() #97
* maxcolor: use new channel API #97
* sliding: use new channel API #97
* intro: use new channel API #97
* new output functions with no need for a cell
* add ncplane_putegc() and ncplane_putsimple(). the former takes an EGC, the latter a simple char less than 0x80. (#97)
* cell_prime: directly load all parts of a cell with immediates
* widecolor: use new output API #97
* boxdemo: properly initialize cells
* slider: total time cap of 5 * delaydemo
* maxcolor: use new output API #97
ncurses getbegy() and friends, as it turns out, check for
a NULL input and return -1. we've been blindly passing
NULL in a few places on the ncurses side--with its own
problems--but that rapidly led to crashes here.
