fend is an arbitrary-precision unit-aware calculator.

Unique features:
* Arbitrary-precision arithmetic using rational numbers
* Full support for complex numbers
* D&D-style dice rolls
* Variables
* Binary, octal, hexadecimal and all other bases between 2 and 36
* Keep track of units, with support for SI, US and UK customary and many
  historical units
* Emacs-style CLI shortcuts
* Trigonometric functions
* Lambda calculus