add a real rudimental shell for no-arg case.
export TIME_FORMAT globally.
add basic command parsing including bug-out

The shell can now be exited (apart from signals)
through the 'exit' command.
Start/Stop will get an honorable mention.
extract commands into own local library

Also redefine return value of checkin_add to return
success state.
add basic support for the list command.
extend shell-list support for date-specification

The list style can now accept a month/year combination argument. So
`checkin -ld 04/2014` in non-interactive mode is equivalent to `list
04/2014` inside of the shell/in interactive mode.
add month-only ability to list in shell.
refactor date handling for list-cmd in shell.
extract shell-command-processing into own file.
integrate non-persistent start/stop

Integrates basic start/stop mechanism into shell. It currently only
reports on times and does not persist them into the database.  Also this
removes the obsolete printNow function.  As a 'replacement' print_time
has been added.
add confirmation of storage for timeslot in shell.
actually store for start/stop in shell.
update README/MANPAGE for current shell status

Also adjust the things-to-be-done list.
And fix bold-faced style error in README.
Merge branch 'shell'