Basic integrated audio/video support, with Ogg implementation.

Basic integrated audio/video support, with Ogg implementation.
* JavaScript video player based loosely on Greg Maxwell's player
* Image page text snippet customisation
* Abstraction of transform parameters in the parser. Introduced Linker::makeImageLink2().
* Made canRender(), mustRender() depend on file, not just on handler. Moved width=0, height=0 checking to ImageHandler::canRender(), since audio streams have width=height=0 but should be rendered.

Also:
* Automatic upgrade for oldimage rows on image page view, allows media handler selection based on oi_*_mime
* oi_*_mime unconditionally referenced, REQUIRES SCHEMA UPGRADE
* Don't destroy file info for missing files on upgrade
* Simple, centralised extension message file handling
* Made MessageCache::loadAllMessages non-static, optimised for repeated-call case due to abuse in User.php
* Support for lightweight parser output hooks, with callback whitelist for security
* Moved Linker::formatSize() to Language, to join the new formatTimePeriod() and formatBitrate()
* Introduced MagicWordArray, regex capture trick requires that magic word IDs DO NOT CONTAIN HYPHENS.