Spanish translation, conflict handling & ignore rules improvements

Improvements for all users:

• The app is now available in spanish. Huge thanks to our translation
  contributors, especially Hernando ❤️
• Files and directories can now only have one -conflict-... suffix at a time.
  Existing ones with multiple suffixes won't be renamed automatically, but in
  case a new conflict occurs, their suffixes will be squashed into a single
  one with the new timestamp. Although this doesn't fix the root causes, it
  should make the symptom easier to deal with. We're sill investigating the
  underlying issues. Expect more fixes soon.
• We fixed a couple of issues preventing user-defined ignore rules to be
  loaded.

See also known issues.

Happy syncing!