note: tests needed changing due to behavioural change in wallet.get_receiving_address()
Previously wallet.get_receiving_address used wallet.db.get_addr_history,
now it (indirectly) uses wallet.get_address_history, which now also considers local txns.
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)
There are now two internal strategies to bump the fee of a txn.
bump fee method 1: keep all inputs, keep all not is_mine outputs,
allow adding new inputs
bump fee method 2: keep all inputs, no new inputs are added,
allow decreasing and removing outputs (change is decreased first)
Method 2 is less "safe" as it might end up decreasing e.g. a payment to a merchant;
but e.g. if the user has sent "Max" previously, this is the only way to RBF.
We try method 1 first, and fail-over to method 2.
Previous versions always used method 2.
fixes#3652
