1.12: Treasury support, added a few config options

• Added Treasury support.
• Added a warning on start-up when legacy coins are detected.
• Added a config option check-for-updates, which allows to disable the version checker.
• Worked on some optimisations.
  • Properly closing json stream leaks.
  • Now using cache, instead of delayed runnables for location limiter.
  • Now caching data (spawner mobs, slime splits, player damage dealt) on entities instead of hash maps.
• Added a config option enchant-increment, which allows setting a coin increment percentage per Looting or Fortune level.
• Some small command improvements.
  • Improved /coins settings.
  • Reworked some other details.
• Grammar fix for English language 'withdrawn' -> 'withdrew'.
• Completely re-styled the config.
  • New and updated information for most config options.
  • Config options now use hyphens, but old-style config options still work.
  • More consequent line breaks.
• Added a config option location-limit-hours, which allows setting the time when a location limiter expires.

Add this to your config: (Or consider resetting your config)

# Show a message to update the plugin on start-up, if the plugin is outdated.
check-for-updates: true

# Set the maximum amount of coin drops (from mob kills) per block location in a
#  specific time. This can be useful to prevent overuse of grinders. Defaults to 1:
#  after 1 kill at x/y/z, it won't drop coins there for the amount of hours set at
#  'location-limit-hours'. Disable by setting to 0. You may want to increase this
#  value if you're using a mob stacker plugin. (1 minute = 0.016667)
#limit-for-location: 1
location-limit-hours: 1.0

# Add more value to coin drops when a Looting or Fortune enchant is used. The
#  configured value is a percentage per enchantment level. Default value is 0.05 =
#  5%. Which means: Fortune/Looting I = 5% coin increase, Fortune/Looting II =
#  10% coin increase and Fortune/Looting III = 15% coin increase.
enchant-increment: 0.05