- Added a metadata field (HashMap<String, Object>) for APSVastAdbreak object (should be constructed before usage). If used, it will add any keys set to the metadata of each APSMediaUnit generated by the adbreak object
- APSMediaPlayer._overlaysDisplayed is now a public field
- Unit metadata keys now contain integers exclusively for determining the offset. The values for prerolls and postrolls are static (0 and Integer.MAX_VALUE)