Function deposit

This function tracks the deposit of cTokens into the pool for the purpose of using as collateral for loans. Since depositing should not cause loans to less collateralized, there are no checks for borrow thresholds in this function.

There is a recalculation of the thresholds and summary statistics for the obligation in this function, but the recalculated values are not used for any security-sensitive purpose. The values can potentially be incorrect but will be recalculated before every sensitive operation anyway.