v0.9.0

• Add a new debug command (#74):
  • debug input lets you automatically generate test cases with your own program
  • debug answer lets you automatically compare your solution's answer to another program provided by you
• Ask which solution file to use when multiple are available (#80)
• Add flag to show stderr in tests (#81)
• Add ability to define kitty's configuration folder via an environment variable (#76)
• Fix failed submission status request (#82)