This change adds a stability value to the api annotation, with
'experimental' as default value.
enum, typedef and event annotations are never exportable, but
api annotations are needed there to make them appear in the
docs.
Nested typedefs are no longer inlined recursively, because the
resulting tables get too wide with the current template.
The single externs/olx.js file describes all of the "options" objects we accept in our constructors. The @typedef annotations are used by the compiler for type checking. The @type annotations include documentation for individual options and serve as externs when compiling a profile of the library. When compiling an application together with the library, the externs/olx.js file is included as one of the sources to provide the @typedef's without generating externs.
If we want to maintain multiple src/*.externs.js files instead of one large externs/olx.js file, we can. But while we are still using Plovr, it makes for easier build configurations to have one file.
This removes the build tasks that generated the build/src/external/src/externs/types.js and build/src/internal/src/types.js files as those are both replaced by the single externs/olx.js file.
