Rename study -> volume globally

No actual code change.
Missed one file rename from last commit
WIP: Change slot/container/asset schema, no models

- Volume is no longer a container.
- The "clip" concept has be raised to the slot level: slot is now a "clip" of a container.
- Assets are largely unchanged, but in the future asset and asset_link may be combined to enforce single-ownership of assets.
- Random POC support functions, currently unused, may be removed.
WIP: updating models for dataset/slot changes

incomplete, broken
WIP: Update Slot and Container, minor schema changes

Also rename title -> name and description -> body globally.
Incomplete, broken.
WIP: AssetContainer (nee AssetLink) work

New SlotAsset class to represent clips of assets within slots.  Tricky
offset accounting got to me.  Broken.
WIP: volumes, containers, slots

Minimal set of models mostly done.  Controllers/views still broken.
Merge branch 'master' into dataset
WIP: controllers/views for container/slot

Start on asset controllers.  Broken.
WIP: asset controllers and store updates

Decided never to allow direct access to container assets, but proxy through
fullSlot instead.  This simplifies a lot.
WIP: toplevel asset definitions

Define new toplevel_ tables for Slots and SlotAssets.

Still broken, but just annotations and thumbnails left.
WIP: record views and compile clean

Probably broken.
Schema fixes and complete container_asset rename

Still probably broken.
Readd annotation functions; minor fixes

Basics are working now.
More minor fixes, more working
Fix asset ms identifiers
Rename offset -> position

offset is apparently a postgres reserved word, and is also a potentially
confusing term (meaning "onset").
Rename Select -> SelectExpr

Because I wanted to do something fancier with Select, but didn't (yet).