changed all of the openmdao.lib.datatypes imports to openmdao.main.datatypes, and made imports of pyV3D and pyzmq conditional
moved pyV3D dependency into openmdao.gui setup.py file
fixed openmdao.lib.datatypes.domain imports that accidentally got changed to openmdao.main.datatypes.domain
fixing some domain tests I broke
added stl files to MANIFEST.in and package_data
added some missing files to openmdao.main distrib
Merge pull request #1476 from naylor-b/condimports

changed pyV3D and pyzmq into conditional imports so that non-gui stuff will still work if they fail to install