Checkpoint: generate raw option
rename raw -> bare at Avi's suggestion

This matches what CoffeeScript calls the same thing.

For compatibility we'll make raw work too, for now.
Pass bare through to the linker.
No-op refactor to internal linker interface.
Implement bare in linker.
Test bare.
Bare is only allowed on the client.
Merge branch 'linker-raw-js' into linker.

Reimplements "client/compatibility" files for the linker branch.

In a package, access this with the {bare: true} option to api.add_files. In a
package, this elevates file-level vars from "file-local" to "package-local" (not
global!)