Add multisig wrapper contract
Clarification and motivation
Multisig wrapper is described here: https://medium.com/tqtezos/multisig-contracts-from-generic-to-wrapping-906d2a783fd3
Its (presumably outdated) implementation is here: https://github.com/tqtezos/lorentz-contract-param/blob/master/src/Lorentz/Contracts/GenericMultisig.hs
We'd like to use it in our project. At this stage it's easier to do if this contract is in this repo because we already depend on it in our projects. So let's add it to morley-multisig
package from !195 (merged).
Acceptance criteria
morley-multisig
package should have generic multisig wrapper. Perhaps some part of code should be shared with generic multisig implementation (from !195 (merged)).