Improvements

[DolevArtzi]

• polar coordinates normal generating alg
• poisson algos, see https://github.com/DolevArtzi/probably-probability/issues/3
• symmetry
• non strict bounds
• naming/ init efficiency: replace self.params with calls to vars(self)... will simplify the code
• print statements in compare.py
• check on Bin pdf k % 1
• ~add axis labels and titles~