Hacky test implementation to perform local broadcaster reads. Needs lots of cleanup.
Previous test version performed the read twice.
Merge branch 'next' into daniel_1886_local

Conflicts:
	src/clustering/immediate_consistency/branch/listener.cc
Completed the local operation interface in listener_t.
Things
Made direct listener operations interruptible, + some cleanup.
== NULL should have been != NULL
Simplified and improved keepalive management for the local listener.
Merge branch 'next' into daniel_1886_local
test/run: improved output and ^C handling

Review 1465 by @larkost
Add versions to our serialization format.
Remove wire_datum_map_t
Use varint for version serialization in RDB_ serialization macros.
Make other serialization functions also use varints ver the version number.
Merge branch 'next' into daniel_2308
Symbols in release mode by default
add SPLIT_SYMBOLS make flag
make STRIP_ON_INSTALL false by default
Add SPLIT_SYMBOLS to README
Remove redundant line