Finish reimplementing commands
Delete the old CommandHandler
Fix the pom.xml
Command system now works, import help, create HelpTopic
Remove duplicate subcommand help topics
Sort the help
Fix deserialization error with Flights due to name collision

Remove usage for commands with no arguments and fix it for those that do

Add some missing min/max parameters
Some misc cleanup
Use Player.sendBlockChange() instead of modifying the world