Save keystrokes frequency

[dacap]

Along command frequency we could record keystrokes frequency. Check for "this-command-keys" in "keyfreq-pre-command-hook" function.

More information: http://www.gnu.org/software/emacs/manual/html_node/elisp/Command-Overview.html http://www.gnu.org/software/emacs/manual/html_node/elisp/Command-Loop-Info.html