2to3 done.

SourceCollectionOnTheFly/SourceCollectionAttributesExtraSourcesSelected.py

+from __future__ import print_function
+
 from astro.main.sourcecollection.SourceCollection import SourceCollection
 
 from astro.main.sourcecollection.FilterSources import FilterSources as BaseFilterSources
 
-from SourceCollectionAttributesSelectedSourcesAll import SourceCollectionAttributesSelectedSourcesAll
+from .SourceCollectionAttributesSelectedSourcesAll import SourceCollectionAttributesSelectedSourcesAll
 
 class FilterSources(BaseFilterSources):
     """

SourceCollectionOnTheFly/SourceCollectionAttributesOneSourcesAll.py

+from __future__ import print_function
+
 from astro.main.sourcecollection.SourceCollection import SourceCollection
 
 from astro.main.sourcecollection.SelectAttributes import SelectAttributes as BaseSelectAttributes
 
-from SourceCollectionAttributesAtleastSourcesAll import SourceCollectionAttributesAtleastSourcesAll
+from .SourceCollectionAttributesAtleastSourcesAll import SourceCollectionAttributesAtleastSourcesAll
 
 class SelectAttributes(BaseSelectAttributes):
     """

SourceCollectionOnTheFly/SourceCollectionAttributesSelectedSourcesAll.py

+from __future__ import print_function
+
 from astro.main.sourcecollection.SourceCollection import SourceCollection
 
 from astro.main.sourcecollection.ConcatenateAttributes import ConcatenateAttributes as BaseConcatenateAttributes
 
-from SourceCollectionAttributesOneSourcesAll import SourceCollectionAttributesOneSourcesAll
+from .SourceCollectionAttributesOneSourcesAll import SourceCollectionAttributesOneSourcesAll
 
 class ConcatenateAttributes(BaseConcatenateAttributes):
     """

SourceCollectionOnTheFly/SourceCollectionAttributesSelectedSourcesSelected.py

+from __future__ import print_function
+
 from astro.main.sourcecollection.SourceCollection import SourceCollection
 
 from astro.main.sourcecollection.SelectAttributes import SelectAttributes as BaseSelectAttributes
 
-from SourceCollectionAttributesExtraSourcesSelected import SourceCollectionAttributesExtraSourcesSelected
+from .SourceCollectionAttributesExtraSourcesSelected import SourceCollectionAttributesExtraSourcesSelected
 
 class SelectAttributes(BaseSelectAttributes):
     """