Moves the TD_FilterBlock from TD_Database to TDPusher.

Previously, a TD_Database managed all filters associated with that
database in a local NSMutableDictionary. This has been removed and
now the TDPusher class holds a copy of the block which defines the
filter.

These changes are reflected in the CDT* level classes.

*filterId is removed from CDTPushReplication
*CDTReplicator is now initialized with an instance of an
CDTAbstractReplication class instead of its NSDictionary representation.
(This doesn't affect the API since this is a 'private' instantiation method.)
*CDTReplicator maintains a copy of a CDTFilterBlock
*CDTReplicatorFactory -oneWay was modified accordingly.

Note: Should I remove CDTReplicatorFactoryErrors as these are not used
anymore?

I don't think TDPusher is the right place for the definition of `TD_FilterBlock`. The block typedef is a more general concept than just replication given its use in `-changesSinceSequence:...`, which might be called by non-replication centric code. Why not TDMisc.h, which is already a bit of a grab bag?