A fix and a test case for gh-664 (bad syntax is accepted in
schema.role.*, schema.user.*, etc).

Check the second argument of role.create()/role.drop(),
user.create()/user.drop(), func.create()/func.drop().

Implement if_exists option for user.drop(), role.drop(),
func.drop().

Add a test case.

Don't start event loop in interactive mode after it ends.

Implement box.schema.user.create(name, { if_not_exists = true })
box.schema.role.create(name, { if_not_exists = true })
box.schema.func.create(name, { if_not_exists = true })

Add tests.

Fixes gh-637.

Use a correct server id to relay snapshot records to a replica
(server id 0 is server id of the snapshot).

Move recover_snap() implementation to memtx_engine.

* Move search form to the left
* Pin left bar (add jquery.pin plugin)
* Move all configuration fields to confval directive
* Move builddirs to separate directories, so less rebuilds.
* Some minor fixes

Conflicts:
	src/box/sophia_engine.h

Fixes gh-778: fiber.id() throws an error for a dead fiber.

Always return fiber id, even for a dead fiber.
Add a test case.

* transaction is yet active on CALL return
* transaction conflicts on commit

Conflicts:
	src/box/replication.cc