add grunt script to predeploy
fix readme example variable name
3.0.5
test for (x-2)^3 compilation, and fix for it
build
fix differentiation of unary '–' operator, and add a test for it.
Fixed differentation of the cosine function, and add tests for it
add factorial test, which will fail because that isn't implemented yet.
Parse postfix !, map it to a new global.factorial function, and write a .default implementation for Integer