v0.3.12

This release makes a few changes relating to 1155s:

1. Allow 1155 transfers using transferNFT to set amount
2. Add 1155 tests:

• demonstrates that 1155s can be minted using a TBA
• demonstrates that multiple 1155s can transferred using transferNFT
• demonstrates that amount param on transferNFT will throw when >1 for 721 tokens