Shulker's Ender Oddities

Added the shulkersenderoddities:df_end_pillar structure.

• Simple puzzles mostly encased in bedrock which contain end-city like loot with a chance of conflicting enchantments. (i.e. fire/projectile protection) Designed with veinminer resistance in mind.
• Structure size ranges from 5x10x5 to 5x30x5
• 0-4 chests spawn per structure with 2 rolls on "minecraft:chests/end_city_treasure" each, plus an extra random enchantment on all compatable items, and durability healed by 30% (not exceeding 100%).

Current spawn conditions: 

Only spawns in end biomes (should include most modded biomes)

Does not spawn within 500 blocks of 0,0

Separation: 16 chunks minimum, 32 average 

(for reference, ~12-16 chunks is a typical default render distance)