Add kind to all units

[adrfantini]

It is often useful to know what kind an unit is.
For example, take the Henry, unit for inductance.

Its definition in unitmath is:

 {
 name: 'henry',
 value: 1,
 offset: 0,
 dimension: { MASS: 1, LENGTH: 2, TIME: -2, CURRENT: -2 },
 prefixGroup: {
 '': 1,
 deca: 10,
 hecto: 100,
 kilo: 1000,
 mega: 1000000,
 giga: 1000000000,
 tera: 1000000000000,
 peta: 1000000000000000,
 exa: 1000000000000000000,
 zetta: 1e+21,
 yotta: 1e+24,
 deci: 0.1,
 centi: 0.01,
 milli: 0.001,
 micro: 0.000001,
 nano: 1e-9,
 pico: 1e-12,
 femto: 1e-15,
 atto: 1e-18,
 zepto: 1e-21,
 yocto: 1e-24
 },
 formatPrefixes: [ 'micro', 'milli', '' ],
 basePrefix: undefined
 }

I would propose to add a field called kind with value INDUCTANCE.
This would allow to simplify whenever you know the kind of a unit, and want to see the available alternatives, e.g. when selecting units for a quantity in a user interface.

Here's an (incomplete!) list of kinds compiled from the defined units and wikipedia:

{
 UNITLESS: { UNITLESS: 1 },
 CURRENCY: { UNITLESS: 1 },
 LENGTH: { LENGTH: 1 },
 AREA: { LENGTH: 2 },
 VOLUME: { LENGTH: 3 },
 TIME: { TIME: 1 },
 TEMPERATURE: { TEMPERATURE: 1 },
 POWER: { MASS: 1, LENGTH: 2, TIME: -3 },
 PRESSURE: { MASS: 1, LENGTH: -1, TIME: -2 },
 FORCE: { MASS: 1, LENGTH: 1, TIME: -2 },
 ENERGY: { MASS: 1, LENGTH: 2, TIME: -2 },
 MASS: { MASS: 1 },
 CURRENT: { CURRENT: 1 },
 CAPACITANCE: { MASS: -1, LENGTH: -2, TIME: 4, CURRENT: 2 },
 INDUCTANCE: { MASS: 1, LENGTH: 2, TIME: -2, CURRENT: -2 },
 IRRADIANCE: { MASS: 1, TIME: -3 }, // added unit kind (W/m²) - COMPOSED UNIT! might consider not supporting
 RESISTANCE: { MASS: 1, LENGTH: 2, TIME: -3, CURRENT: -2 },
 POTENTIAL: { MASS: 1, LENGTH: 2, TIME: -3, CURRENT: -1 },
 ACCELERATION: { LENGTH: 1, TIME: -2 },
 SPEED: { LENGTH: 1, TIME: -1 },
 VOLUMETRIC_FLOW: { LENGTH: 3, TIME: -1 },
 INFORMATION_RATE: { BIT: 1, TIME: -1 },
 INFORMATION: { BIT: 1 },
 ANGULAR_VELOCITY: { ANGLE: 1, TIME: -1 },
 ANGULAR_ACCELERATION: { ANGLE: 1, TIME: -1 },
 ANGLE: { ANGLE: 1 },
 FREQUENCY: { TIME: -1 },
 CHARGE: { CURRENT: 1, TIME: 1 },
 SOLID_ANGLE: { SOLID_ANGLE: 1 },
 RESISTIVITY: { MASS: 1, LENGTH: 3, TIME: -3, CURRENT: -2 }, // added unit kind (ohm meter) - COMPOSED UNIT! might consider not supporting
 CONDUCTANCE: { MASS: -1, LENGTH: -2, TIME: 3, CURRENT: 2 },
 DENSITY: { MASS: 1, LENGTH: -3 },
 MAGNETISM: { MASS: 1, LENGTH: 0, TIME: -2, CURRENT: -1 },
 LUMINOUS_INTENSITY: { LUMINOUS_INTENSITY: 1 },
 LUMINOUS_FLUX: { LUMINOUS_INTENSITY: 1, SOLID_ANGLE: 1 },
 YANK: { MASS: 1, LENGTH: 1, TIME: -3 },
 VISCOSITY: { MASS: 1, LENGTH: -1, TIME: -1 },
 MOMENTUM: { MASS: 1, LENGTH: 1, TIME: -1 },
 ANGULAR_MOMENTUM: { MASS: 1, LENGTH: 2, TIME: -1 },
 AREA_DENSITY: { MASS: 1, LENGTH: -2 },
 RADIATION_EXPOSURE: { LENGTH: -2, TIME: 1 },
 MAGNETIC_FLUX: { MASS: 1, LENGTH: 2, TIME: -2, CURRENT: -1 }, // added unit kind (weber) - https://github.com/ericman314/UnitMath/issues/65
 ACTIVITY: { TIME: -1 }, // missing unit (Bequerel) - https://github.com/ericman314/UnitMath/issues/65
 MOLAR_CONCENTRATION: { LENGTH: -3, AMOUNT_OF_SUBSTANCE: 1 },
 SUBSTANCE: { AMOUNT_OF_SUBSTANCE: 1 },
 ILLUMINANCE: { LUMINOUS_INTENSITY: 1, SOLID_ANGLE: 1, LENGTH: -2 }, // corrected from original unitmath (lux) - https://github.com/ericman314/UnitMath/issues/66
 ELASTANCE: { MASS: 1, LENGTH: 2, TIME: -4, CURRENT: -2 },
 SPECIFIC_VOLUME: { LENGTH: 3, MASS: -1 },
 JOLT: { LENGTH: 1, TIME: -3 },
 SNAP: { LENGTH: 1, TIME: -4 },
 RADIATION: { LENGTH: 2, TIME: -2 },
 WAVENUMBER: { LENGTH: -1 },
}