Give every package its own directory in packages/
including single-file packages.
* packages/markchars/markchars.el: Provide itself (bug#11915).
* packages/markchars/markchars.el (markchars--render-confusables): Don't
quote lambda.
* packages/markchars/markchars.el (markchars-mode): Use font-lock-flush
when available.