Conflicts:
	src/test/unit-agrad-rev/matrix/cholesky_decompose_test.cpp
	src/test/unit/distribution/multivariate/continuous/inv_wishart_test.cpp

Feature/fix ldlt

added stronger language indicating that success() must be true before using the other functions within LDLT_factor

Expand documentation to make it clear that you must call compute() if you use the default constructor.