Changes to support emission lines throughout, especially ITC

[rpiaggio]

• Adds a method to find the nearestLine in the distribution, also relocate nearestBand.
• Adds a standard Display[BigDecimal] and forwards Display instances for refined types.
• Explicit display and serialization for velocity units, since the derived ones from coulomb are not ITC friendly.
• Move Quantity -> Measure extension methods to a syntax package.