BUG: Test if 'issubclass' only if 'isclass' is True
BUG: Test if 'issubclass' only if 'isclass' is True

Calling 'issubclass' without verifying that the object passed as a parameter
is a class may return 'issubclass() arg 1 must be a class' error message
when the user tries to autocomplete text in an IPython interactive console.

Change-Id: I3330c83de60cd136db5dbc3b3b92355a1ee846c0

hjmjohnson/ITK,stnava/ITK,malaterre/ITK,Kitware/ITK,thewtex/ITK,vfonov/ITK,Kitware/ITK,LucasGandel/ITK,spinicist/ITK,stnava/ITK,stnava/ITK,blowekamp/ITK,fbudin69500/ITK,spinicist/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,hjmjohnson/ITK,blowekamp/ITK,Kitware/ITK,stnava/ITK,hjmjohnson/ITK,blowekamp/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,LucasGandel/ITK,Kitware/ITK,BRAINSia/ITK,spinicist/ITK,stnava/ITK,vfonov/ITK,vfonov/ITK,LucasGandel/ITK,spinicist/ITK,stnava/ITK,blowekamp/ITK,thewtex/ITK,thewtex/ITK,LucasGandel/ITK,hjmjohnson/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,InsightSoftwareConsortium/ITK,stnava/ITK,richardbeare/ITK,PlutoniumHeart/ITK,malaterre/ITK,fbudin69500/ITK,LucasGandel/ITK,malaterre/ITK,spinicist/ITK,blowekamp/ITK,BRAINSia/ITK,malaterre/ITK,BRAINSia/ITK,vfonov/ITK,richardbeare/ITK,vfonov/ITK,richardbeare/ITK,richardbeare/ITK,thewtex/ITK,blowekamp/ITK,malaterre/ITK,PlutoniumHeart/ITK,vfonov/ITK,spinicist/ITK,BRAINSia/ITK,fbudin69500/ITK,stnava/ITK,LucasGandel/ITK,stnava/ITK,BRAINSia/ITK,fbudin69500/ITK,richardbeare/ITK,malaterre/ITK,vfonov/ITK,blowekamp/ITK,Kitware/ITK,spinicist/ITK,Kitware/ITK,fbudin69500/ITK,fbudin69500/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,thewtex/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,hjmjohnson/ITK,LucasGandel/ITK,LucasGandel/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,hjmjohnson/ITK,malaterre/ITK,hjmjohnson/ITK,PlutoniumHeart/ITK,spinicist/ITK,Kitware/ITK,richardbeare/ITK,malaterre/ITK,blowekamp/ITK,thewtex/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,spinicist/ITK