See NEWS for details

Merge dev branch (#43)

* improve test_dsep

* fix bug in test_dsep for dsemRTMB

* fix another bug in last commit

* fix another bug in last commit

* update test_dsep

* updates to test_dsep

* fix crash in simulate.dsem ...

... when variance = "random" but without random effects.  This now reverts to submodel variance = "none"

* fix bug in last commit

* import from ggm manually

* add example for total_effect

* run document on last commit

* adding random-seed for test_dsep

* make CI happy

* adding options for how to impute data

* make CI happy

* update test_dsep somewhat

* expanding Details about latent variables

* adding d-sep paper scripts

* removing them again

* export make_matrices

* Update make_matrices.R

* Update NEWS.md

* fix NOTE on CRAN check

* add model-description and re-organize pkgdown page

* Update model-description.Rmd

* Update model-description.Rmd

* Update model-description.Rmd

---------

Co-authored-by: Jim Thorson <James.T.Thorson@gmail.com>