ENH: adding 2d/3d specialization for rigid registration + averaging of images for template creation (averaging bug fixed) 
ENH: adding 2d/3d specialization for rigid registration + averaging of images for template creation (averaging bug fixed) 

acaprihan/Lungs,stnava/ANTs,dawnsong/ANTs,fbudin69500/ANTs,dawnsong/ANTs,fliem/ANTs,acaprihan/Lungs,dawnsong/ANTs,DaisukeMiyamoto/ANTs,DaisukeMiyamoto/ANTs,fbudin69500/ANTs,fbudin69500/ANTs,dawnsong/ANTs,fbudin69500/ANTs,stnava/ANTs,dawnsong/ANTs,fbudin69500/ANTs,acaprihan/Lungs,acaprihan/Lungs,DaisukeMiyamoto/ANTs,DaisukeMiyamoto/ANTs,dawnsong/ANTs,stnava/ANTs,DaisukeMiyamoto/ANTs,stnava/ANTs,DaisukeMiyamoto/ANTs,stnava/ANTs,fliem/ANTs,acaprihan/Lungs,stnava/ANTs,acaprihan/Lungs,fliem/ANTs,fliem/ANTs,fliem/ANTs,DaisukeMiyamoto/ANTs,stnava/ANTs,fbudin69500/ANTs,dawnsong/ANTs,fliem/ANTs,fbudin69500/ANTs,fliem/ANTs