Compound.js v0.4.0

In this version, Ethers.js v5 is a peer dependency. Users of npm <7 will need to install Ethers version 5 as a peer dependency. In case they do not, they will see a warning in the command line log when installing the package. Additionally, only necessary files are shipped to npm in new releases. Thank you to @PaulRBerg for the contributions in this release.