Introducing a new speed group feature!

• Allow players to change their fly speed, from -10 to 10. Negative values indicate reverse directions.
• Able to define the range of speed allowed with speed groupings, see new config.yml
• Permission to give users the speed group is flyperms.speed.<groupname>

Other fixes

• Fix logging where severe is logged as info
  
• Minor code cleanup and optimisations

As always, happy flyinggg!

~ Ben