(#1778) - copyedits for change event docs
(#1734) - leveldb simultaneus write race condtions
(#1734) - leveldb doc writing race conditions
(#1860) - Fix info.doc_count for leveldb
(#1809) - proper through stream for all docs, and handle errors
(#1898) - don't wait until we have all the changes before calling onChange
(#1872) - optimize utils.parseDoc()
(#1889) - more websql perf improvements
(#1897) - idb perf improvements for get/allDocs

Similar to what was done for WebSQL, this caches
the docCount as well as minimizing the calls to
isDeleted and merge.winningRev. The winningRev
is also stored in the by-seq store, similar to how
the winningSeq is stored in websql.
(#1653) - server sent events for replication