- fixed jQuery selector escaping + fixed iframe loader timeout
added missing objects to public API of EpubCfi (exceptions / errors)
now Media Overlays playback engine captures the document-load-start event in order to pause its internal state whilst the iframe is loading, and performing its layout.
fixed edge-case: multiple XHTML per single SMIL (100% pass epub-testsuite, AFAICT)
clean-up Media Overlays highlighter API + stub code for multiple sync granularities