column_chunk default ct. deleted as it had no sense. Basic tests are created for it.
Added segment id to resend queries and put back the actual sending of resend queries.
On timeout try to ask for missing chunks a couple of times before throwing error.
Merge remote-tracking branch 'origin/master' into engine-refactor

Conflicts:
	test/engine_test.cc
Chunks need to be removed from missing list even if they are the expected ones.
Merge pull request #36 from starschema/engine-refactor

Engine refactor