Fix "removePending: sequence %lld not in set" warnings

Fixes #42
Workaround for truncated _changes feed responses

If TDSocketChangeTracker gets an unparseable response whose beginning
looks like the expected JSON, assume the socket got cut off by some
intermediary and go through the usual retry mechanism.
Fixes #241.
Fix memory leaks (reference cycles) in replicator

Fixes couchbase/couchbase-lite-ios#37

Conflicts:
	Source/CBLMultipartReader.h
	Source/CBL_Puller.m
	Source/CBL_Pusher.m
Persona 'origin' URL should not end with '/'

It's not entirely clear whether it should or shouldn't, but the examples on the Persona developer site show it without.
A disagreement about this was breaking logins in LiteGap, because the strings didn't match.
Fixed bug where view arguments that had spaces where not having '+' symbols removed before querying the database.
Bump version to 1.406 (alpha candidate 1)