Custom quotes were added in 4f129a3e and began with !, however, this
required quoting "!reverse" (used for the cycle-values command), which
is inconvenient, and was not taken into account when ! was chosen for
custom quotes. Also, ` is more natural for quoting than !.
This does break backward compatibility with the earlier form of custom
quotes, but at least we didn't make a release yet since custom quotes
were added (the last release - 0.33[.1] doesn't support it).
Avi Halachmi (:avih)
73c9509720