Students T-Test

Added functions for Students T-Test one sample and independant sets and a function to convert a t-value to a p-value. Not sure about the naming, if you would like me to change the function names and resubmit requrest, let me know. I have tests, I will add examples next week and I would like to add dependant sets after that.
A minor point, but it came up in one of the discussions below. I've already removed OneSampleTTest, because it became redundant. The remaining funciton is now call TTest. While it is often referred to as a Student's T-Test, it is technically a Welch's T-Test. The difference being that a Student's T-Test doesn't work if the variance is different, Welch's corrects for that. Because the terms are sometimes used interchangeably and sometimes the difference is important, I would drop the label entirely. While it's terse, I would suggest simply calling it stattest.T