Add offline mode

[asiliuk]

Allow saving schedule for use in offline

• It should not be ON by default, it should be a choice of user when schedule is cached
• Maybe cache pinned\favorites?
  • How to make sure it is cached when favorites were synced from iCloud
• Add autorefresh
  • It should do it in background to make sure it is in actual state
  • It should do it when receive new name\id to cache but no current cache (iCloud sync)
• There should be a way to clear cache from settings
  • Should it remove from favorites?
  • Should it cache again if I would choose autocache favorites?