STYLE: Improve readability and const correctness of ImageIORegion.
STYLE: Improve readability and const correctness of ImageIORegion.

Change-Id: I9254bc96980505f4306608b7b45f9d021cb6e4bb

jcfr/ITK,biotrump/ITK,eile/ITK,spinicist/ITK,ajjl/ITK,blowekamp/ITK,jcfr/ITK,ajjl/ITK,fedral/ITK,msmolens/ITK,biotrump/ITK,fbudin69500/ITK,jmerkow/ITK,thewtex/ITK,jmerkow/ITK,jmerkow/ITK,heimdali/ITK,spinicist/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,malaterre/ITK,PlutoniumHeart/ITK,atsnyder/ITK,spinicist/ITK,LucasGandel/ITK,heimdali/ITK,fbudin69500/ITK,LucasGandel/ITK,hjmjohnson/ITK,spinicist/ITK,hendradarwin/ITK,spinicist/ITK,heimdali/ITK,jmerkow/ITK,malaterre/ITK,zachary-williamson/ITK,hendradarwin/ITK,BlueBrain/ITK,stnava/ITK,biotrump/ITK,ajjl/ITK,LucHermitte/ITK,fedral/ITK,eile/ITK,eile/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,BRAINSia/ITK,Kitware/ITK,hjmjohnson/ITK,blowekamp/ITK,jmerkow/ITK,vfonov/ITK,LucasGandel/ITK,LucasGandel/ITK,blowekamp/ITK,jmerkow/ITK,InsightSoftwareConsortium/ITK,zachary-williamson/ITK,biotrump/ITK,malaterre/ITK,BRAINSia/ITK,LucHermitte/ITK,richardbeare/ITK,vfonov/ITK,msmolens/ITK,fedral/ITK,LucasGandel/ITK,biotrump/ITK,malaterre/ITK,ajjl/ITK,stnava/ITK,heimdali/ITK,InsightSoftwareConsortium/ITK,biotrump/ITK,hendradarwin/ITK,thewtex/ITK,vfonov/ITK,jcfr/ITK,ajjl/ITK,hjmjohnson/ITK,msmolens/ITK,atsnyder/ITK,BlueBrain/ITK,Kitware/ITK,msmolens/ITK,InsightSoftwareConsortium/ITK,jcfr/ITK,LucasGandel/ITK,atsnyder/ITK,jcfr/ITK,jmerkow/ITK,BRAINSia/ITK,heimdali/ITK,BRAINSia/ITK,spinicist/ITK,thewtex/ITK,blowekamp/ITK,eile/ITK,hendradarwin/ITK,BlueBrain/ITK,vfonov/ITK,Kitware/ITK,BlueBrain/ITK,LucHermitte/ITK,stnava/ITK,LucHermitte/ITK,biotrump/ITK,stnava/ITK,BRAINSia/ITK,blowekamp/ITK,thewtex/ITK,biotrump/ITK,atsnyder/ITK,spinicist/ITK,hjmjohnson/ITK,richardbeare/ITK,vfonov/ITK,spinicist/ITK,fbudin69500/ITK,eile/ITK,ajjl/ITK,malaterre/ITK,hendradarwin/ITK,BRAINSia/ITK,LucHermitte/ITK,PlutoniumHeart/ITK,hendradarwin/ITK,hjmjohnson/ITK,fedral/ITK,fedral/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,richardbeare/ITK,BlueBrain/ITK,fbudin69500/ITK,hendradarwin/ITK,zachary-williamson/ITK,InsightSoftwareConsortium/ITK,heimdali/ITK,LucHermitte/ITK,richardbeare/ITK,eile/ITK,atsnyder/ITK,hendradarwin/ITK,blowekamp/ITK,malaterre/ITK,vfonov/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,eile/ITK,malaterre/ITK,hjmjohnson/ITK,Kitware/ITK,richardbeare/ITK,thewtex/ITK,jmerkow/ITK,Kitware/ITK,jcfr/ITK,thewtex/ITK,PlutoniumHeart/ITK,LucasGandel/ITK,jcfr/ITK,ajjl/ITK,BRAINSia/ITK,msmolens/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,stnava/ITK,fedral/ITK,spinicist/ITK,vfonov/ITK,stnava/ITK,heimdali/ITK,zachary-williamson/ITK,heimdali/ITK,BlueBrain/ITK,stnava/ITK,fbudin69500/ITK,malaterre/ITK,jcfr/ITK,LucasGandel/ITK,blowekamp/ITK,fbudin69500/ITK,eile/ITK,fedral/ITK,zachary-williamson/ITK,ajjl/ITK,fedral/ITK,fbudin69500/ITK,eile/ITK,msmolens/ITK,LucHermitte/ITK,BlueBrain/ITK,atsnyder/ITK,thewtex/ITK,msmolens/ITK,zachary-williamson/ITK,blowekamp/ITK,malaterre/ITK,msmolens/ITK,atsnyder/ITK,atsnyder/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,stnava/ITK,vfonov/ITK,vfonov/ITK,zachary-williamson/ITK,BlueBrain/ITK,atsnyder/ITK,zachary-williamson/ITK,hjmjohnson/ITK,richardbeare/ITK,richardbeare/ITK,LucHermitte/ITK,zachary-williamson/ITK