Correct/improve dragbox docs
Use @classdesc notation (continuing #2178)
Use @api annotation instead of @todo api
Document olx.format.PolylineOptions

This was mistakenly annotated with `@todo stability` (which does nothing).
Removing old code
Remove @todo stability annotation (this has no effect)
Use @observable annotation instead of @todo observable
Extra annotations for build.py as well
Merge pull request #2306 from tschaub/new

Remove old code.
Merge pull request #2305 from tschaub/todo

Replace @todo annotations.
Remove test/ol.html

This file was used when Plovr was used for running the tests.
Remove examples/loader.js

That script was used when Plovr was used for running the examples.
Remove bin/closure

And use the depswriter.py script from Closure Library downloaded by closure-util.
Add a task to run the tests once with PhantomJS

The test.js task starts the development server and runs the tests in PhantomJS.  As mentioned in the readme, when running the tests continuously during development, it is more convenient to start the dev server and visit the root of the test directory in your browser.

Later we can bring in Karma to drive PhantomJS and other browsers, but this simple "run once" task is useful for the CI job.
Merge pull request #2307 from elemoine/build

Build-related clean-ups
Use inheritDoc for ol.source.XYZ#setTileUrlFunction
Merge pull request #2296 from elemoine/settileurlfunction

Use inheritDoc for ol.source.XYZ#setTileUrlFunction
Merge pull request #2309 from tschaub/test

Add a task to run the tests once with PhantomJS.
Add sinon as a dev dependency
Add mocha and mocha-phantomjs as dev dependencies