This commit adds basic keypool mark-used and topup:
- try to topup the keypool on initial load
- if a key in the keypool is used, mark all keys before that as used and
try to top up
This commit moves functions start_node, start_nodes, stop_node and
stop_nodes functions into the BitcoinTestFramework class. It also moves
the bitcoind_processes dict and coverage variables into BitcoinTestFramework.
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.
John Newbery