Many changes to support a second mode of operation. Pynche can now be

Many changes to support a second mode of operation.  Pynche can now be
run either as a standalone application (by running pynche or
pynche.pyw), or as a modal dialog inside another application.  This
can be done by importing pyColorChooser and running askcolor().  The
API for this is the same as the tkColorChooser.askcolor() API, namely:

    When `Okay' is hit, askcolor() returns ((r, g, b), "name").  When
    `Cancel' is hit, askcolor() returns (None, None).

Note the following differences:

    1. pyColorChooser.askcolor() takes an optional keyword `master'
       which if set tells Pynche to run as a modal dialog.  `master'
       is a Tkinter parent window.  Without the `master' keyword
       Pynche runs standalone.

    2. in pyColorChooser.askcolor() will return a Tk/X11 color name as
       "name" if there is an exact match, otherwise it will return a
       color spec, e.g. "#rrggbb".  tkColorChooser can't return a
       color name.

There are also some UI differences when running standalone vs. modal.
When modal, there is no "File" menu, but instead there are "Okay" and
"Cancel" buttons.

The implementation of all this is a bit of a hack, but it seems to
work moderately well.  I'm not guaranteeing the pyColorChooser.Chooser
class has the same semantics as the tkColorChooser.Chooser class.