Show

Updated mechanism for method-specific option setting. Still work
in progress, but code now much cleaner.

One additional routine, ``show.where``, can have its method
parameters set at runtime. More to follow as the method-setting
technqiue progresses.

The experimental operator forms of ``show`` such as ``>`` and
``>`` have been withdrawn. The operator style isn't consonant with
Python philosophy, complicated the code base, and only partially
worked. Interesting idea, but experience suggests they are not
worth the trouble.

Changed name of parameter ``sep`` in ``hr``, ``title``, and
``sep`` methods because discovered it was conflating and
interfering with the ``sep`` parameter in the main options. The
horizontal separator character that is repeated N times is now
addressed as ``char``. Also fixed bug in temporary turning off of
output from those methods; fixed.

New ``show.pretty`` module. If you ``from show.pretty import *``
then pretty-printing will be automatically turned on, and a
Unicode solid square will be prefixed to every line, to make it
easier to visually distinguish debug output from normal program
output.

Bumped test coverage to 80%. In the process, discovered and fixed
some bugs with ``show.props``. Most things that can be basically
unit-tested, are. Largest remaining test coverage gaps concern
operation under different I/O managers--esp. IPython and the
standard Python REPL--that will require integration testing.

Quashed second bug related to IPython and its ``%run`` command,
especially as used by the Enthought Canopy IDE.

Fixed problem with IPython when program run with the ``%run``
command. Fix esp. important for users of Enthought Canopy IDE,
which uses this mode of execution extensively.