Commitment sma support

[CalabashSquash]

Motivation

We need support for arbitrary frontrunning intervals (which can be many factors larger than the updateInterval). This requires being able to store data for an arbitrary number of update intervals at a particular point in time.

Note that this PR introduces loops, but the amount of iterations still has a limited upper-bound. The upper-bound is frontRunningInterval / updateInterval (e.g. if frontRunningInterval = 5 * updateInterval, then there will be at most 5 iterations.

Changes

PoolSwapLibrary

• Add function appropriateUpdateIntervalId
  • This calculates the correct update interval ID based on the current time, frontrunning interval and update interval
    PoolCommitter
• Removed userMostRecentCommit, userNextIntervalCommit, totalMostRecentCommit and totalNextIntervalCommit
  • The use of these was essentially just hardcoding support for only two update intervals.
  • The purpose of this PR is to generalise that part of the code to support any number of update intervals being stored at one particular point in time.
• Changed commit to now store commitment data in the commitment corresponding to the result of a call to PoolSwapLibrary.appropriateUpdateIntervalId.
• executeCommitments now loops through a theoretically unbound number of update intervals (should never actually happen if pool is upkept in a reasonable amount of time.
• updateAggregateBalance now loops over all un-aggregated balances. As per the note above, this still has a strict upper bound.
• getAggregateBalance has now been updated to reflect the above changes.