Use a value class

Added 8 integer clamping functions

Added scientific notation and dice expressions (cheaply as operators)


lots of new stuff

Added sgn(x) to .calc

- reverted previous commit (now that was a bad idea)

- store expression and tokens as members of Calculator rather than being passed around as parameters

Major refactor: moved calculator routines into a Calculator class.

(0) -100 -10 +10 tip