Added triangular and non uniform distribution

[brendan-bath]

I've added the triangular and non uniform distribution. For each distribution I mapped a standard uniform distribution value to the given distribution by putting the value through the percent point function. in the case of the non uniform linearly decreasing value I assumed the value would intercept the lower bound at 2/(upperBound - LowerBound). From there a gradient is worked out such that the percent point function at the upper bound would be equal to 1.

[gpampara]

Thanks for the PR! I'm curious about the formulation and just want to check a few things before we merge this.

[brendan-bath]

Feel free to ask my any questions if you have any concerns/confusion.