Previously we failed to decode min_final_cltv_expiry properly if the highest bit was 1:
in practice, we could not pay invoices that had a value in [16-31] or [512-1023].
Many invoices use a value around 144, so this was simply unnoticed.
also update default value to follow BOLT change:
c5693d336d
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)
SomberNight
Janus