Coulomb collections

[erikerlandson]

An attempt to implement #50

[erikerlandson]

As an efficiency measure I tried creating a subclass of scala.Conversion that can also operate directly on "raw" values inside a QuantityVector. Doing this will break ABI compatibility, and so I wanted to verify whether it actually improves efficiency before I commit to it.

I benchmarked this using a couple of test functions:

def bench1[V, U](qv: QuantityVector[V, U])(using cnv: scala.Conversion[Quantity[V, U], Quantity[Double, Meter]]): QuantityVector[Double, Meter] =
    qv.map(cnv)

def bench2[V, U](qv: QuantityVector[V, U])(using cnv: QuantityConversion[V, U, Double, Meter]): QuantityVector[Double, Meter] =
    QuantityVector[Meter](qv.values.map(cnv.raw))

The bench2 variation that uses the raw conversion is > 7x faster. Furthermore, it produces significantly less load on the garbage collection, so the benefits are even bigger.

This demonstrates the benefits of breaking MIMA with QuantityConversion, and also justifies the benefits of defining QuantityVector in the first place.