Compile entire code base on build check

Currently, the `check` target builds `build/ol.js`, and therefore doesn't catch errors in code that is not used or exported.

For example, if you introduce an error in `dragrotateandzoominteraction.js` the `check` target won't detect it.

This PR suggests making the `check` target build `build/ol-all.js`, and extending `ol-all.json` to compile the `exports` as well.