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.
Organize special rng tests for (inv)wishart
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' 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
Merge pull request #663 from stan-dev/feature/issue-644-inv_wishart_rng

Fixes #644. Feature/issue 644 inv wishart rng