Delete everything and start from scratch
Initial pack skeleton
DCG describing marks recorded in a text file

Each time a user clocks in, we create a mark on the timeline.  The mark
contains a timestamp and a note (space separated list of words).  These
DCG predicates describe this text format.  They can both parse and
generate mark lines based on mark values.

There's also supported for an antiquated mark line format in which a
username and tags field existed.
Trim choicepoints inside mark//1

This saves every caller from having to wrap it in once/1.
Implement 'clk in' and 'clk out'

This also creates a build rule 'make all' which compiles clk into a
statefile which can be executed directly.  This avoids slowness
re-compiling the source each time.  It also avoids problems caused by
missing module dependencies since they're all packaged in the state
file.
Recompile state file for each 'make all'

Don't try to encode dependencies in the Makefile.  Any of several Prolog
modules could change and require a rebuild.  Just perform the
compilation every time.
Factor out now_mark/1

This utility creates a mark whose timestamp is now.  I'll want to reuse
this code shortly.
Polish command comments a little
Create 'clk edit' command

Edit the timeline file that would be used for recording a brand new
mark.  If the most recent mark was created in the previous month, this
may try to edit a file that doesn't exist.  I can fix that if it ever
becomes a real problem.

Closes #10
Merge branch 'prolog'