ivy

modify build_submodules to use homebrew ssl

makefile for installing ivy in dev mode on macOS

mutate build_submodules.py according to https://github.com/stellar/scp-proofs/blob/3e0428acc78e598a227a866b99fe0b3ad4582914/docker/Dockerfile#L24-L25

notice a bug in collections

correct the type of the local index value