- added EMAN2.3 support, deprecated 2.12
- _bispec was renamed to _invar - these changes affect ctf and refine2D_bispec protocols
- refine2d_bispec won't work without input bispectra anymore, so input changed from particles to eman ctf protocol
- fix pixel size in output models for initial model protocol and for the input reference in refine easy, so that eman does not rescale it when not necessary
- fix wrong filename in autoboxer for bg refs
- add new initial model sgd protocol
- EMAN2DIR renamed to EMAN2_HOME to be consistent with other plugins