Apply auto width to math images in documentation
Fix duplicate Distributions documentation header links.
Remove unused variable.
Add option to automatically draw multiple plots to different files.
Replace bitwise & with short-circuit &&.
Add Chain plot method with argument ptype as a vector.
Redefine ptype argument default for Chain plot method.
Update documentation for Chain plot methods.
Add detail and clarity to the draw method documentation.
Revert "Apply auto width to math images in documentation"

This reverts commit 491a892905775d19646810eacb6b471f0dc18461 which was
intended to fix small width display of math on RTD, but did not.
Add error checking and fix variance calculation.
Update documentation version to 0.3.7.