Drop support for GHC 6.10.
Use Cabal's test-suite feature to define the tests.
Update IPv6 tests to work on machines with ::1 but no ipv6 "localhost".
Use Cabal's benchmark feature to define the benchmarks.
Test 'addMatch' instead of the deprecated 'listen'.
Clean up call cancellation handling in DBus.Client.

The new code doesn't depend on the deprecated function
'addMVarFinalizer', and should be generally more reliable.
Update extra-source-files for new test/benchmark filenames.