Configurable btree chunk size
New fields for chttpd and friend
Store #full_doc_info{} records in the seq tree

This improves the performance of compaction and replication by not
requiring a btree lookup for every row in the by_seq tree at the cost of
storing extra bytes on disk.
Use exported functions for code upgrades

We need to make sure we're not holding onto anonymous functions for
indefinite lengths of time. Due to erlang hot code upgrades processes
will die randomly after two upgrades when they're holding old code.
Load validation functions on first write

Clustered databases need to consult the cluster to grab their
validation functions. To avoid unnecessary loading as well as some race
conditions of the load we delay the load until the first attempt to
write to the database.
Disable conflict detection for _local docs

This can lead to breakage for internal cluster replication.
Enable clustered multipart-mime uploads

We have to insert a middleman process into the parsing so that each of
our copies can retrieve the data as its uploaded.
Remove use of init:restart/0

We've had issues with this so avoid it when we can.