Maker compiler warnings are fatal
Use market data environment in mtm test
Remove InstrumentValuationContext

As this was just a container for a Valuer trait variable it
could be replaced throught by the valuer itself.
Refactor position calculation

Essentially moving code around. Added 'positions' method to the Valuer
trait, and moved the SVD position calculation to its own file.
Minor changes to Qty

`compare` method was dubious, possibly not reflexive
stricter about return types of Qty builder methods, and
implicits
SVDPositions - make loss of precision clearer

Scales of hedges changed to DblQty from BDQty
Refactor CommoditySwap

rename `market` to `index`
SwapValuer was unnecessarily matching on index type - behaviour
was the same regardless
PositionPivotReport