Pass around display instead of renderer.

Added option for stale period.

Use already defined constant for lock wait, instead of introducing a new one.

Added include file for defines.

Removed unnecessary parent in plugin definition.

Fixed queue locking.
Removed debug logging.

Added queueing functionality.

Current options available to caller during prefetch.

Added default expirations values.
Added watchdog debug messages.
Implemented integration with views (cache plugin).

Added default settings.