variables reported by PyChecker.

__togglegentype(): PyChecker accurately reported that the variable
__gentypevar was unused -- actually this whole method is currently
unused so comment it out.

to color constants (i.e. red constant, green constant, blue
constant).  But I haven't hooked this up yet because the UI gets more
crowded and the arrows don't reflect the correct values.

Added "Go to Black" and "Go to White" buttons.

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.

separators later

the StripViewer class.

    self.__chips now contains the list of rgbtuple values for the
    chips named i - 1 (Tkinter counts from 1, we count from zero).
    The chip number was just the index + 1.  This means color lookup
    need not do an itemcget(), it can just index into __chips.

    instead of calling __canvas.itemconfigure(), we glom up a huge Tcl
    script and call tk.eval() directly.  Actually we do many appends
    to a Python list, then string.join() them together into one huge
    string.  This reduces the overhead of Tkinter but making one fast
    call to Tcl.