SERVER-12517 Add listIndexes command

Add comments on command
SERVER-15873 add missing .h declaration for msgassertedNoTrace
SERVER-15873 massert trace not needed when splitAndMove fails
SERVER-15562 Search neighbors for density estimation with 2d index
SERVER-10515 removed unused file mongos_persistence_stubs.cpp
SERVER-15887 Add tests for ipv6 hostname parsing.

Closes #846

Signed-off-by: Benety Goh <benety@mongodb.com>
SERVER-14638: Move global sethbmsg into ReplCoord
SERVER-15869: Provide config version for each member in replSetGetStatus
SERVER-15867: primary should response to heartbeats as electable
SERVER-15880 AutoGetCollectionForRead should always free its collection lock
SERVER-15880 Delete path should not try to create database
SERVER-15824 renameCollection should commit the destination coll drop
SERVER-13951 Fix rollback of CollectionMap
SERVER-13951 Allow rollback of dropping an index
SERVER-13951 KVEngines shouldn't drop anything when renaming.
CollectionInfoCache::reset should reset index keys under X lock
Merge remote-tracking branch 'nextdoor/master'
SERVER-15496 Code movement to facilitate ripping out legacy replication code
SERVER-15877 Give secondaries 1 second to catch up in replSetStepDown
SERVER-15614 Move inProcCmd to a separate file and clean includes

It is currently in instance.cpp, which is very cluttered. This change is
in preparation for the db.currentOp fix.