Documented prefetchCount for MQ.bind
Removed LibreOffice doc_data.txt output and added the filename to .gitignore
PR follow up:
 * Wrapped previews related data in a previews object
 * Changed queue.unbind so that the queue is no longer destroyed.
 * Cleaned up PP start procedure
 * Added the content id to the logger
 * Increased thumbnail size
 * JSDoc cleanup