logging: warnings logging

• Refactors warnings reporting to use logging system by default.

• Adds best practice error handling documentation.

• Adds StreamHandler to warnings logger in debug mode.

• Unhides DeprecationWarning.

• Adds support for sending warnings to Sentry.

• Removes custom warnings wrapper.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>