WT_DATA_SOURCE handles, called when the handle is discarded,
intended to allow general cleanup when the database is closed.
Re-work the BDB KVS and Memrata support to handle multiple open
databases, that is, get rid of all of the globals.
a default of wiredtiger_extension_unload.
Rename "entry" load extension entry point to be "load", rename the default
from wiredtiger_extension_init to wiredtiger_extension_load, to match.
a new function wiredtiger_extension_api(WT_EXTENSION_API **pp).
Write some WT_EXTENSION_API documentation.
Remove WT_SESSION::msg_printf, add a new msg_printf extension function
instead, convert test/format to use it.
Quit using __UNUSED in the extension code, use explicit (void) casting,
it's cleaner.
Quit installing the nop and reverse_collator libraries.
Rename the session.create block_compressor configuration strings
"bzip2_compress" to "bzip2", and "snappy_compress" to "snappy".
Add documentation for configuring the built-in bzip2 and snappy
configuration in applications.
