v0.24.0

Added

• General dimensional unit algebra: values carry a dimension vector (length, mass, time, current, temperature, amount, luminosity, information, angle, currency) and an exact scale; *, /, powers and roots combine dimensions, addition and comparison require equal dimensions (10m × 10m = 100 m^2, (5 volts) / (2 ohms) = 2.5 A, 1 mph * 1 hour = 1 mi, sqrt(2m) is an error).
• A data-driven unit database in data/units/ with SI base and derived units, all SI prefixes (including µ/μ/u), binary prefixes, Imperial/US, electrical, information, angle and temperature units, plus English and Russian aliases (feet, metres, м, км, ч).
• Unit expressions such as m/s, m⋅s−1, m·s⁻¹, m s^-1, km per hour, kg·m²/s² and kg / (m^-2 s^2), as quantities and as conversion targets.
• Compound quantities 5 feet 10 inches, 1 meter 20 cm and 6'2".
• Affine temperatures: 20 celsius is 293.15 K, 25 °C in °F is 77 °F, and arithmetic on °C/°F is rejected as in Numbat.

Changed

• m after a number is the metre and min the minute; 5m reads as minutes only in an explicit time context (5m in s, 1h + 5m, now + 5m).
• Products of compound units that were previously rejected (5 kg * 9.8 m/s^2) now evaluate, and meters is displayed as m.