The contract artifacts should remain as standard compiler output during development. Fields should only be removed/added prior to being published in `@0x/contract-artifacts`. This PR adds the `yarn transform` script to `@0x/contract-artifacts` to facilitate this.
Going forward, `abi-gen-templates` will have to support both standard artifacts and modified artifacts if they diverge, since the templates are used for `contract-artifacts`/`abi-gen-wrappers` (modified artifact) *and* development in all the `contracts/*` packages (standard artifact).
This PR makes the following changes to `contract-artifacts`:
- remove `evm.bytecode.linkReferences` from all artifacts
- remove `evm.deployedBytecode` and `sourceTreeHashHex` from Coordinator artifact
- prettify all artifacts (whitespace only changes)
