Fixed a bug in the previous commit’s unit test
Add “_local_seq” property to doc passed to map block

Its value is the sequence number of the revision. The map function can
emit this as the key (or part of the key) to sort the index chronologically
like a _changes feed.
FMDB fix: Better error handling in FMResultSet
Better validation of “_id”, “_rev”, “_deleted”, “_attachments” properties
Fixed spurious CBLDocumentChange.inConflict value

When a previously nonexistent document is created via a pull replication,
the inConflict flag was mistakenly getting set (because technically a new
branch of the document is being created; it just happens to be the first
one.)
Fixes #243