We save location where transaction was started, in case we try to nest.
There's now no error case; db_exec_mayfail() is the only one.
This means the tests need to override fatal() if they want to intercept
these errors.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Not the nicest code, but it allows us to store the bip32_max_index so
that we don't forget our addresses upon restart. We could have done
the same by retrieving the max index from our index, but then we'd
forget addresses that don't have an associated output. Conversion
to/from string is so that we can store arbitrary one off values in the
DB in the future, independent of type.
Rusty Russell
Christian Decker