Move bloom and feerate filtering to just prior to tx sending.

This will avoid sending more pointless INVs around updates, and
 prevents using filter updates to timetag transactions.

Also adds locking for fRelayTxes.

src/net.h

@@ -357,7 +357,7 @@ public:
     // a) it allows us to not relay tx invs before receiving the peer's version message
     // b) the peer may tell us in its version message that we should not relay tx invs
     //    unless it loads a bloom filter.
-    bool fRelayTxes;
+    bool fRelayTxes; //protected by cs_filter
     bool fSentAddr;
     CSemaphoreGrant grantOutbound;
     CCriticalSection cs_filter;