* Previously we had "Frame X" and "Start of Frame" hardcoded in the event
browser, and the end of frame was in many cases assumed to be a present call.
However with the in-application API this is not necessarily true.
* Presents are now serialised separately in all APIs and displayed wherever they
happen in the frame, and if there is no present at the end of the frame an
"End of Capture" marker is inserted. Similarly API-defined captures are not
given a potentially misleading frame number.