multi-transfer mvp

MVP version of the multi-transfer function which allows a user to send funds to multiple addresses in one func call to save fees.

Note that it's not atomic, if sender runs out of funds before sending to all addresses, the previously successful ones are not rolled back, we just stop processing the rest of the transfers.

prc20 demo

This release was used to demo the progress we've made in implementing an equivalent ERC20 tokens standard on our chain as well as a proof of concept atomic swap.