Adding support for the Python coverage.py tool.

This assumes that coverage.py has been run in such a way to produce its
standard XML output. This uses the Cobertura schema and should be somewhat
generalizable.
Pull the coverage.xml file from the binary directory.

This is more consistent with typical CMake-driven development. Thanks
go to Rolf Eike Beer for making this point on the developers list.
Adding a test for Python coverage.py xml output.
Fix the failing coverage test by removing an off-by-one error.
Cleaning up logging output and eliminating redundant comments.
Improving python coverage error handling.

Properly incrementing the Error variable and output a message with the
ERROR context where appropriate.
Merge topic 'Add-coverage.py-Coverage' into next

ddc5cbe Improving python coverage error handling.
eeb110a Cleaning up logging output and eliminating redundant comments.
a1bf495 Fix the failing coverage test by removing an off-by-one error.
cb2d8b5 Adding a test for Python coverage.py xml output.
5d6b090 Pull the coverage.xml file from the binary directory.
6ee1404 Adding support for the Python coverage.py tool.