Add ability to enforce only one tagtime is running.
Basic documentation for tagtime.
Merge branch 'upstream'
Merge pull request #17 from pfenwick/master

Run only a single tagtime instance, plus bonus documentation.
Show what the user was last doing, for easier ditto.
Show last-doing in bold/cyan if Term::ANSIColor is available.
Extra blank line after prompt.
Merge branch 'master' of https://github.com/pfenwick/TagTime
Tweaks
The strip fn shouldn't trim trailing whitespace

Adding that broke the cntpings utility. There's a function trim
for removing trailing and initial whitespace.
License placeholder
Going with apache license; thanks Justyn!
Allow tags to include '-' characters.

You can still do subtraction expressions by making sure there are
spaces included.  Eg:

    cntpings foo.log entertainment - tv

No spaces are taken as a tag:

    cntpings foo.log ice-cream
New LICENSE file thanks to Justyn and Joseph