Potential confusion between `mean` of a Gaussian Distribution function and `diststats` `mean`

[HKaras]

The Gaussian distributions are specified with a mean value for the peak. This can be confusing as this is the mean of the function not necesarily the distribution which is limited by the choice of r axis. This is especially true when the gaussian distrbutions have non-physical values below 1 nm.

Maybe the Gaussian distribution parameter should be adjusted to make this clearer. One option would be to rename it to center similar to the dd_skewgauss.

[stestoll]

center seems reasonable, although mean seems fine as well.