refactor audio recording into struct

Also now runs Wait() to free resources if arecord dies.
readme: add awesome-numen
readme: add sprec
readme: mention ~/.config/numen/phrases
bump copyright years
readme: add min-trailing-silence note
deprecate /usr/local/share/vosk-models
install: separate building and installing

Also installs to /usr/lib not /lib, removes ./install-vosk-musl.sh
and $NUMEN_MANPAGE_DIR, and bumps dotool.
readme: public-inbox -> numen
gofmt, use 0o octal literals
add buttondown and buttonup actions
install: add -buildvcs=false
readme etc: tweak
scripts: gsub(" "a" ", " "b" ") in scripts/tweak
remove PACKAGING.md
readme: add packages
readme: tweak
phrases: "scrunch" -> "kludge"
test: use a dummy dotool