install: missing target is an error
install: adjust log messages, drop ~/ subst

bash 4.1 changed the quoting slightly, so ~ is now expanded and \~ isn't
(but if I use \~ then I get the backslash in older versions). Let's just
drop it entirely.
install: s/log()/say()/ to be closer to lib.bash
install: always log when $DEBUG set
install: -e mode is unnecessary
install: use lib.bash
install: mention .ssh/config update
bash: rain: turns out I keep a lot of stuff in ~/tmp
bash: rain: add ~/@foo/ to no-trash list
ssh: hosts (+ grex.org)