trk start <project> (if tracking project: stop-and-start, aka switch)
trk start at <YYYY-MM-DD hh:mm> <project>
trk on <project> (alias for start)

  Starts tracking of a project. If 'at' is given, start-time
  is overridden to the given time.

  Future expansion:
  If a project was already tracking, that project will be stopped
  at the startingpoint of the new tracking, i.e. implicitly switching.

trk note Comment will be timestamped

  Adds a comment/note to the tracking. The note will not
  affect tracked time, but will be included in detailed reports.

trk activity <task>
trk activity at <YYYY-MM-DD hh:mm> <task>

  Starts tracking of an activity within the project; think task
  or sub-projects. Activities will be tallied within the project
  like the "main project", while time counts to both activity
  and project. 

  Future:
  Only one activity can be ongoing at the same time,
  so starting a new activity while one is ongoing stops the current
  and starts the new one.

trk main
trk main at <YYYY-MM-DD hh:mm>

  Stops tracking ongoing activity, and keeps tracking project.

trk pause <optional description>
trk back

  Adds an activity to the project that is not counted on
  the project. Pauses will be listed on detailed reports,
  but not on terse, standard and verbose reports.

trk charge <customer>

  Will set a customer name as meta-information. Setting the
  charged customer will replace any previously set value.

trk status

  Displays current project, charged customer (if any),
  start time for this session, time spent on this session,
  time spent on project total,
  current activity with start time and time spent this session.

trk stop
trk stop at <YYYY-MM-DD hh:mm>
trk off (alias for stop)

  Stops tracking of project, with implicit stopping of any
  current activity.

trk report terse <project>
trk report <project>
trk report verbose <project>
tkr report details <project>

   Gives a tracking report for the given project.

   Terse reports include:
     * project name
     * charged customer
     * total time accumulated

   Standard reports include:
     * project name
     * charged customer
     * session start and end datetimes and time elapsed on session
     * total time accumulated

   Verbose reports include:
     * project name
     * charged customer
     * session start and end datetimes and time elapsed on session
     * activity start and end datetimes and time elapesd on activity
     * note texts w/datetime
     * time accumulated per named task
     * total time accumulated

   Detailed reports include:
     * project name
     * charged customer
     * session start and end datetimes and time elapsed on session
     * activity start and end datetimes and time elapesd on activity
     * pauses with start, end, comment and elapsed time
     * note texts w/datetime
     * time accumulated per named task
     * total time accumulated

trk projects

   Lists all known project names