defined eadtoolbox.__all__
reduced complexity; removed ui package

Command-line UI methods moved to top level module. Made top-level
modules callable.

- eadtoolbox.ui.validate.validate -> eadtoolbox.validate.validate
- eadtoolbox.ui.sandbox.start_sandbox -> eadtoolbox.sandbox.start
removed unwanted globals in validate

- session
- server

(copy and paste cruft!)