Add more quantity types

Here's a list of modules that I'd like to add at some point - pull requests for any of these are welcome! (Take a look at existing modules for inspiration.) I've listed how I think each quantity's units should be defined, either as a base unit (Moles, Candelas, etc.) or as a rate/product of other units (in which case the units type will be a type alias of the form Rate x y or Product x y). Note that there are some dependencies here - can't add the VolumetricFlow modules without the Volume module, or LuminousIntensity without SolidAngle!

Kinematics/dynamics

• AngularSpeed (RadiansPerSecond = Rate Radians Seconds) (thanks @katjam!)
• AngularAcceleration (RadiansPerSecondSquared = Rate RadiansPerSecond Seconds) (thanks @katjam!)
• Torque (NewtonMeters = Product Newtons Meters) (thanks @gampleman!)

Volume

• Volume (Cubed Meters) (thanks @katjam!)
• VolumetricFlow (CubicMetersPerSecond = Rate CubicMeters Seconds)
• Density (KilogramsPerCubicMeter = Rate Kilograms CubicMeters) (thanks @katjam!)
• SubstanceAmount (Moles) (thanks @ukarim!)
• Molarity (MolesPerCubicMeter = Rate Moles CubicMeters) (claimed by @lenards)

Electromagnetism

• Inductance (Henries = Rate Volts (Rate Amperes Seconds)) (thanks @ukarim!)
• Capacitance (Farads = Rate Coulombs Volts) (thanks @ukarim!)

Photometry

• SolidAngle (Steradians)
• LuminousFlux (Lumens)
• LuminousIntensity (Candelas = Rate Lumens Steradians)
• Illuminance (Lux = Rate Lumens SquareMeters)
• Luminance (Nits = Rate Candelas SquareMeters)