Video support:
* Clean MP4, MOV and 3GP videos — device info, location, timestamps
  and other metadata wiped in place, streams never re-encoded
* Templates now apply to videos too (keep / remove / randomize)
* Share videos or mixed photo+video selections to the app

New features:
* Metadata viewer: inspect any photo or video and preview exactly
  what a template removes, keeps or randomizes
* First-launch tutorial explaining how and why to use the app
* Cleaned videos can be saved to Movies
