Bugfix Release 0.1.1

Bugfix Release v0.1.1

• No Content Block creation possible in non composer mode, thx to @mkrappitz fixes #1
• Saving existing Basic creates duplicate, thx to @nhovratov fixes #2
• Checkbox "items" property saved incorrctly, thx to @nhovratov fixes #3
• prefixType must not be saved with empty string, thx to @nhovratov fixes #4
• Add soft fail for currently not supported FileType handling, thx to @baderpaul
  and @nhovratov #7
• Increase dark mode support, thx to @jonaseberle

Detailed commits you can find in development repo.