added in softmax and normal_p, though normal_p will become normal_cdf after the name change
added in softmax and normal_p, though normal_p will become normal_cdf after the name change

stan-dev/stan,stan-dev/math,stan-dev/stan,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/stan