STYLE: Use SmartPointer direct conversion constructors
STYLE: Use SmartPointer direct conversion constructors

Use GetPointer is not longer needed to convert between related types
when referenced by a SmartPointer.

Change-Id: I439968597cd0d7d3da1c325449c974e46dd0587e

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