Add fluid support

[elizabethlfransen]

Addresses issue #12

Adds fluid support to the experience crystal

• Does not add fluid of its own
• Allows any valid xp fluid (using forge:experience or forge:xp_fluid)
• Uses first fluid found under these tags as the default fluid to pump out but supports all xp fluids
• Allows item interaction (bucketing fluid)
• uses conversion rate of 20 mb / xp point (seems to be standard)
• Updates a few version required for testing
• Adds pipez and mob grinder utils (used for testing)

[MelanX]

Thank you for adding this. I merge this and will adjust a few little things, really thanks for helping. I planned to add an own fluid but this solution is much better.