* spike new scanner
* add existing items to new scanner
* add collection refresh actions
* add tv show metadata and posters
* update metadata and posters when nfo/poster files are updated
* add "remove" action, test for all supported file extensions
* update statistics when primary video file is updated
* reflect that collections are "sourced" from nfo
* implement most scanning actions
* cleanup
* fix startup
* cross-platform scanner tests
* first pass at refresh-all-metadata by source
* add version to startup logs
* lock media source during refresh
* fix local media source "name" in collection editor
* optimize scanning so playouts only rebuild when necessary
* support more poster file types
* more scanning improvements; check for missing posters during scans
