Finished implementation of proper equippable weapons

[DrkSephy]

This pull request contains the following changes:

• Cleaned up console.logs and comments.
• Documented isInArray method.
• Added validWeapon property to base_enemy, and base_player.
• Updated button spawning checks.
  • Only spawns initial unequip button if the first weapon was actually a valid weapon to equip.
  • Only spawns the equip button if the selected weapon was actually a valid weapon to equip.