Erbele 3.8.6

• improved dark mode support: new default colors for dark mode; improved cursor appearance; added dark mode color settings to settings dialog; change colors if appearance settings are changed in macOS settings dialog
• fixed errors related to file protection in macOS Catalina:
  • #2 fixed error when installing command line utility
  • #3 fixed error when opening or saving files that are protected
• improved some translations
  • #8 changed german translation for "Snippet" from "Codeschnipsel" to "Textfragment"
• started transcoding Sourcecode from Objective-C to Swift to make Erbele more future-proof
• changed minimum target macOS version from 10.12 to 10.13 (removed support for macOS Sierra; if you use macOS Sierra, please use Erbele 3.8.5)