Fixes#1143 (and possibly others). Before this commit,
(index plus gap limit) addresses are imported on sync,
and addresses used by maker/taker in coinjoin are imported,
but when a deposit occurred, bumping the index, further
addresses were not imported. The effect was that it was
possible, if doing a series of deposits to multiple
external addresses in a Qt session, to end up depositing
to an address that was not yet imported. And this results
in the user needing to rescan for Core+JM to recognize the
coins.
After this commit, we ensure all 'gap limit forwards'
addresses, which are displayed as potential deposit addresses
in Joinmarket-Qt, are imported before the display.
Adam Gibson
ac8b173508