Added functions and test to calc module

Added those new functions : 
* "what is the square root of 9",
* "what is the cube of 3", (also works with square)
* "what is 3 to the power of 4", "what is 3 to the 4", "what is 3 power 4", 
* "what is the 11 percent of 200", "what is 11% of 200",
* "what is 26 mod 5"