Note a regression about --help
Make --debug show the gtk completion setting
Fix UnicodeWarning when adding non-ASCII text (#20)

Fixes the warning that appears on Python 2 if you've got gtk-completion
enabled (which is the default setting) and try to add an entry with
non-ASCII text.

There was probably a logic error as well (duplicate entries might show up
in the completion popup).

The fix costs us a little extra memory usage (a Python set object), but
the strings in it should be shared with the self.history list, so it
shouldn't be much.
Speed up entry addition (#21)

When I added auto-reloading by polling the timelog mtime every second I
somehow forgot that adding a new entry to the end of the file also
*changes the mtime*.  And so the next tick will reload *everything*.
Which takes a while, when your timelog.txt is 20 thousand lines ling.