This commit fixes the module-level docstrings for the tests and helper
modules in qa. Many of these tests were uncommented previously - this
commit ensures that every test case has at least a minimum level of
commenting.
Fixes a bug in AcceptBlock() in invoking CheckBlock() with incorrect
arguments, and restores a call to CheckBlock() from ProcessNewBlock()
as belt-and-suspenders.
Updates the (overspecified) tests to match behavior.
John Newbery