* Add MultiPaymentSplitter
with ERC20 support on top of the existing PaymentSplitter
* consistency and linting
* Add MultiPaymentSplitter tests
* fix lint
* add changelog entry
* add MultiPaymentSplitter to documentation
* rework PaymentSplitter to include ERC20 support by default
* remove test file for MultiPaymentSplitter
* fix lint
* completelly split erc20 and token tracking
* address some PR comments
* add notice about rebasing tokens
* fix minor error in tests
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>