pyzo branch merged into devel. work continues in pyzo branch

[Edward K. Ream]

Merging pyzo into devel is a convenience for me while work continues in the pyzo branch. The changes:

- The --global-docks command-line argument no longer ever creates dummy global docks.

- The pyzo_in_leo plugin is functional, modulo well known bugs. It creates all of pyzo's global docks.

- leo/plugins/pyzo contains all of pyzo's sources, using @clean.

These sources contains traces I use during development. They contain @nopyflakes directives as needed so that writing any of these files should result in no errors. All of these sources pass perfect import tests

- LeoPluginsRef.leo contains @clean nodes as just described.

Summary

I don't expect any significant problems.  Let me know if I'm wrong.  I'll continue to work in the pyzo branch.

When the pyzo_in_leo plugin is enabled, you should see pyzo's global docks.

When this plugin is not enabled you will no longer see the dummy test docks.

Edward