Ignore non-sync invs and don't relay invs if we are not yet caught up.

We originally wanted to also not fetch orphan parents in this commit, however,
I have discovered that if you are doing a main sync from a peer, if it
sends you an orphan you must fetch it, else you ahven't fetched
everything it told you about and thus it will nto send you end more invs
from the main sync.

So we always fetch orphan parents, but we still don't fetch from
non-sync peers (all invs from them will be unsolicited). Seems to fix some hangs
with multiple peers.
Remove peers from duplicate map *before* we restart sync.

Just in case this ordering causes problems.