Add ol.format.Binary

This PR adds binary support to `ol.Format`.

Reading binary data is done using `ArrayBuffer`s, if available, otherwise (i.e. on IE9) it falls back to using `VBArray` to create an `Array.<number>`, where each array element is a byte. This abstraction is handled by `ol.binary.Buffer`.

Right now, only sequential reading of binary data, byte-by-byte, is supported, via the `ol.binary.IReader` interface. If/when random access is needed, appropriate methods can be added to `ol.binary.Buffer`.

Right now, the only binary format in progress is TWKB. See #1615 and another PR about to be opened.