Changes in this version:

• Add text as a synonym for string (e.g. 5 to text)
• Add units gf (gram-force), pond and variations thereof
• Add at unit (technical atmosphere, equivalent to kgf/cm^2)
• Add Torr unit (equivalent to 101325/760 Pascals)
• Add kat/katal unit of catalytic activity
• Add r/q/R/Q prefixes for ronto, quecto, ronna and quetta respectively
• Add variants like sqcm, cm2, cbcm and cm3 for common length units
• Add Cmd+k / Ctrl+k or Ctrl+l to clear the web UI output
• Fix multiline input not being visible in the web UI
• Persist command history in the browser's local storage when using the web UI
• Change default exchange rate source to the European Central Bank as their API is more reliable.
• Fix quetta prefix (equivalent to 10^30)