This patch fixes the following bugs:

* Configured selection highlighting colors were ignored
* Updating highlighting in the config dialog would cause
  non-Python files to be colored as if they were Python source

Additionally, adding and removing of ColorDelegators to the Percolator
was not being done in an organized fashion, causing multiple colorizers
to be present simultaneously in certain cases. This patch ensures that
there will always be at most one colorizer present in the Percolator.

This patch also reduces code duplication by grouping colorization code
into EditorWindow.ResetColorizer, and having __init__ let ResetColorizer
do its thing.

There is one side effect to this patch - applying a new highlighting
scheme or renaming a file causes the screen to "blink". This can be
avoided without too much work, but IMHO is minor enough to leave as it is.

The first patch contained a bug - a window opened using the "New Window"
menu option would not be colorized.

This patch removes the assumption that EditorWindow.ResetColorizer will
be called by IOBinding code, by calling ResetColorizer during __init__
anyways. This means that in some cases it will be called multiple times,
but this has no noticeable effect since the window is not shown until
afterwards. (In the worst case scenario, the colors would "blink" once
or twice.)

r60844. Thanks for the patch!