Tidy up em2d docs.


git-svn-id: https://svn.salilab.org/imp/trunk@17252 e91f8c7b-0e32-4433-a9ac-4502d39a4eab
suppress warning when merging from develop remote

git-svn-id: https://svn.salilab.org/imp/trunk@17253 e91f8c7b-0e32-4433-a9ac-4502d39a4eab
improve warning message

git-svn-id: https://svn.salilab.org/imp/trunk@17254 e91f8c7b-0e32-4433-a9ac-4502d39a4eab