Append single ops, rather than prepending.
Fix test where limit was in wrong place.
Change test after changing how limit is added.
update RenderTree instance for PipelineBuilder
tweak LIKE test to provoke type inference bug
preserve annotations for equal nodes (Fixes #220)
Fixes #206 by adding a new optimization pass that deletes unused fields.

1. add new file for optimizers in mongodb; create pipelinezipper and begin work on optimization to delete unused fields; prepare to move old optimizers into new package
2. delete old optimizer now that it's been relocated to new optimize package
3. got optimizer working for planner test cases, with updating test cases to reflect new behavior
4. add test case that was not passing before most recent optimization pass
quick update to readme
code cleanup
Fix test where limit was in wrong place.
Explicitly choose >>> or &&&.
Merge remote-tracking branch 'origin/209-incorrect-group-by-plan' into 209-incorrect-group-by-plan-merge

Conflicts:
	src/test/scala/slamdata/engine/physical/mongodb/planner.scala
Merge pull request #228 from sellout/209-incorrect-group-by-plan-merge

fix single-op insertion
Allow aggregate to use disk.

Partial fix/workaround for #227.
Merge pull request #232 from sellout/209-incorrect-group-by-plan-merge

Allow aggregate to use disk.
Whoops. Tests updated.
Merge pull request #233 from sellout/209-incorrect-group-by-plan-merge

Whoops. Tests updated.
fix RenderedTree.diff to label changed nodes using the type
fix wartremover config, leaving it commented for now (see #236)
Merge pull request #237 from mossprescott/minor

Couple of little cleanups for debugging; wartremover config