[Enhancement] Class Restriction: Blacklist

[goflishMC]

In the item_generator module there's a section for class restrictions.
-Add an option to use as blacklist
-Reverse, false (use as whitelist, this should be the default)
-Reverse, true (use as blacklist, the classes listed will not be able to use the items)

class:
  reverse: true/false #this is the line to set whitelist/blacklist
  '1': Warrior,Cleric