The confusing mixture of byte index and character count meant that every
use of .substr was incorrect; replaced by slice_chars which only uses
character indices. The old behaviour of `.substr(start, n)` can be emulated
via `.slice_from(start).slice_chars(0, n)`.
OS X's terminfo uses the hex representation of the first character of
the terminal name as the directory name.
Ubuntu seems to use /lib/terminfo instead of /usr/share/terminfo, at
least on the one machine I have access to.
