Remove pyutilib namespace package; defer TPL import tests

jsiirola commented 4 years ago

Fixes: #N/A

Summary/Motivation:

This PR does two things:

Removes the use of namespace packages from pyutilib. After we consolidated the bulk of PyUtilib into a single repository, there aren't (maintained) pyutilib capabilities outside of this repository. Removing the namespace packaging simplifies several things (including plugin imports)
Reworks how optional dependent libraries are imported so that many optional dependencies (notably pkg_resources and openpyxl) are only imported "on demand". This significantly speeds up importing pyutilib.

Changes proposed in this PR:

remove namespace packages pyutilib and pyutilib.component
rework optional dependency imports

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coveralls commented 4 years ago

Coverage increased (+0.03%) to 61.069% when pulling b7f5c75674f5051c81f47e7494b189907faa1464 on import-updates into 6591015234b400865573eebcb710e534e60ce13d on master.

jsiirola commented 4 years ago

@whart222, @blnicho: this is ready to review.

jsiirola commented 4 years ago

Closing this to split it into two PRs

PyUtilib / pyutilib