Dynamic Volume Trades

Molecule supports dynamic volume (aka as-generated) trades, where a trade's volume is based on a forecast that changes over time. In a dynamic-volume trade:

1. The Trade uses a Product that is enabled for dynamic volume (by setting the UOM to %).
2. The Trade's volume is set to a percentage (so 70% instead of 10 MW).
3. The Trade is linked to an Asset that contains the forecast. 
   1. The Asset's volumes are updated from time to time.
   2. When the Asset's volumes are updated, the Trade's volume actualizes to the new volumetric number.
   3. The Trade's valuations reflect the actualization that was effective for the valuation date.
   4. This can be repeated multiple times (no limit on the number of actualizations).