Addresses ([#229])
This allows effective feerates (PPM) to be computed for earnings and
expenses.
This PR updates the schema automatically. Downgrading to previous
will require manual DB migration (but is possible). Downgrade
commands are in a comment in EarningsTracker.c
This commit modifies the schema of EarningsTracker to allow storing
and accessing earning and expenditure data in specific time ranges.
All existing strategies and reports still use all data from all time
so this PR should not change any balancing behavior.
After we've run w/ this for a while we'll have time-based data
collected and can evaluate how to improve the strategies.
