This PR moves statistics to its own file, seperates getBlockMetas
into its own function, and removes the timeEnd parameter from
calculate statistics. The ending time is now computed directly from
the start time and the duration, to enforce that we only collect
data for the provided duration.
At larger tx sizes (e.g. > 10000) we were spending non-neglible
amounts of time in tx creation, due to making the final bytes random.
The slower the send loop, the less accurate it is at measuring the time
tendermint took. (As we can't reach the promised contract of the given rate)
There really isn't much need for that randomness, so this PR makes it
such that only the txNumber gets bumped between txs from the same
connection, thereby improving sendloop speed and accuracy.