Consolidation tweaks
 - Makefile: make target alltests really run all the tests
 - cv.py: rewrite cv_report based on Dimension.report()
New routine pop0: safely pop 0th element of a list
 - test_Util.py: test for new routine pop0()
 - util.py: new routine pop0() to pop the 0th item from a list with throwing
   an exception on an empty list
Add field 'cart' to checkablestable and use as a dimension
 - Checkable.py:
    - add field 'cart' to database and use it
    - parse 'ls -P' output based on '\t' rather than regexp
 - Dimension.py: tweaks to generalize Dimension to work for 'cart' as well as
   'cos'
 - rpt_lib.py: add cart section to cv report
 - test_Checkable.py: allow for 1) presence of field 'cart' in database and
   Checkable object, 2) fdparse() splitting 'ls -P' output on '\t'
 - test_Dimension.py: add test for new method addone()