stopEarning()
Callable by an earner OR on behalf of an earner if earner was removed from the Approved TTG earners List
Allows a user to stop earning yield on their M balance. balanceOfuser after the call of this function will be rewritten to storeprincipalOfEarningSupplyMToken,earner∗indexnow
Saves balanceOfMToken,earner=principalOfEarningSupplyMToken,earner∗indexnow
Saves totaNonEarningSupply+=balanceOfMToken,earner
Saves totalPrincipalOfEarningSupply−=principalOfEarningSupplyMToken,earner
Sets isEarningMToken,earner=false
Calls updateIndex.