Unify unit test file structure

[Orson Maxwell]

Currently the name of a unit test coincides with the name of the module it tests. We need a naming convention for test files - something along these lines:

• modulename_test.py;
• modulename_unittest.py;
• classname_unittest.

[Orson Maxwell]

On the second thought I think the proper naming should be like this:

[package]_<modulename>_test.py

Examples: ui_zipfont_test.py logger_test.py (omit root package name) etc.

[Алексей Котиков]

Commit edc0610