C.R.E.A.M. Collateral Swap

Note

• this is work in progress
• UI process walkthrough:
  1. user clicks some ui to swap collateral 100 A tokens to collateral B tokens
  2. front end calls flashloanLender to borrow 100 A tokens
  3. crAToken calls this contract's function onFlashLoan, and send 100 A tokens to this contract
  4. swap (100-flashloanFee) A tokens for B tokens
  5. deposit B tokens and get crBTokens
  6. send crBTokens to the user
  7. grab crATokens from the user
  8. withdraw from crATokens and get 100 A tokens
  9. by now the contract has (100 + flashloanFee) A tokens, ready to be grabbed by crAToken for flashloan repayment