* 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