ncvisual_render() now returns the number of cells emitted
rather than just 0/-1. -1 is still returned on failure.
Rather than 0 for length meaning "all possible length", it
now means 0, and -1 means "all possible length". All demos,
tests, and PoCs have been updated. #422
* sync up some docs #244
* sync README and man page
* notcurses_output() man page work
* pull attr/channels from output functions #244
* witherworm: clean up explicit moves #244
* still more man page work
* notcurses_lines, last of the man pages i think
* panelreel man page #244
* debian: ruby-ronn->pandoc
* debian: full multiarch compliance
* debian: symbols file
* pandoc: fix syntax for lexgrog
* fm6.mkv: strip audio
* pandoc: fix up apropos man syntax #249
* ncurses_lines man page