Worked on cleaning up and reorganizing all the code that handles numcopies
settings. Much nicer now. Fixed some bugs.

As expected, making the preferred content numcopies check look at
.gitattributes slows it down significantly. So, exposed both the slow and
accurate check and a faster version that ignores .gitattributes.

Also worked on the test suite, removing dependencies between tests.
This will let tasty-rerun be used later to run only previously failing
tests.
