* Remove check for sign with privkey in init_cmdline
* Add with_privkey and with_wallet variants of signtransaction command
* Add unit tests for signtransaction_with_privkey and signtransaction_with_wallet commands
note: low R grinding would not have to be duplicated if we trusted the caller
to have done it already (as is the case with the classes in ecc.py), and if
we propagated the choice of "random_k" as part of the nonce_function passed
to libsecp256k1 (which is not currently done)
The few other cases that used SimpleConfig.get_instance() now
either get passed a config instance, or they try to get a reference
to something else that has a reference to a config.
(see lnsweep, qt/qrcodewidget, qt/qrtextedit)
- commands are async
- the asyncio loop is started and stopped from the main script
- the daemon's main loop runs in the main thread
- use jsonrpcserver and jsonrpcclient instead of jsonrpclib
