v0.4-mc17w43b

Additions:

• Added b7s:entity/get_block_id* functions to get the numeric ID of a block at or under a certain entiy;
• Added b7s:entity/get_block_dv* functions to get the numeric data value of a block at or under a certain entiy.

Changes:

• Upgraded directory structure to match the new data pack structure used in Minecraft 1.13.