Possible fix for inv_wishart_rng
inv_wishart_rng: transpose needed here to be consistent with R chol behaviour
Possible fix for both inv_wishart_rng and wishart_rng
wishart_rng: turn scale into a symmetric matrix and adds an unit test.
added von_mises_rng with error checks

still need to add goodness of fit test
Organize special rng tests for (inv)wishart
Update von_mises.hpp

Convention is that sign = 0 at 0
Change delta to s

Poor copy of original.
Ensuring range is 0 to 2pi 

I hope I used the correct syntax. Intent is to add 2pi and then take fmod of 2pi.
Only once times pi

Peter is right, need only addition of one pi to move into [0, 2pi]
Spoke too soon

Not working somehow; old way worked. Leave for now.
Marcus's suggestion & use TWO_PI

Implement Marcus's suggestion to ensure crazy mu's don't push answers out of the range and use TWO_PI since it is defined above already.
wishart_rng and inv_wishart_rng now only takes the lower part of the scale matrix
(inv_)wishart_log: use only the lower portion of the outcomes and scale matrices and adds tests to check that property
Make more explicit that scale and outcomes matrices of (inv_)wishart are symmetric and positive-definite
inv_wishart_log: fix wrong matrix type
Merge branch 'develop' of https://github.com/stan-dev/stan into feature/issue-644-inv_wishart_rng
Merge branch 'develop' of https://github.com/stan-dev/stan into develop
 Merge branch 'develop' into feature/issue-644-inv_wishart_rng

Conflicts:
	src/stan/prob/distributions/multivariate/continuous/inv_wishart.hpp
	src/stan/prob/distributions/multivariate/continuous/wishart.hpp
fixed rounding error for normal_cdf, normal_cdf_log with tests