ENH: add multivariate normal option to return the effective rank
MAINT: remove return_rank optional argument, add .rank multivariate_normal_frozen attribute, add tests
MAINT: learn how to use frozen distributions
MAINT: aggregate covariance matrix info into an object
MAINT: do not silently reduce dimensionality, but allow reduction with a forcing flag
TST: more tests for singular covariance matrices
DOC: one eigh -> one call to eigh
DOC: add the allow_singular flag to more parts of the docs
MAINT: add mvn error checking
MAINT: typos
DOC: move __init__ docstring into the class docstring
Merge pull request #3141 from argriffing/mvn-return-rank

ENH: add multivariate normal option to return the effective rank