Remove -limitfreerelay and always enforce minRelayTxFee in the mempool (except from disconnected blocks)
Remove -relaypriority, the option was only used for the ability to allow free transactions to be relayed regardless of their priority. Both notions no longer apply.
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.
