ENH: added test to check that Matrix returns a copy of the vnl matrix
ENH: added test to check that Matrix returns a copy of the vnl matrix

Tests the fix in fede4b8.

malaterre/ITK,LucasGandel/ITK,hjmjohnson/ITK,LucasGandel/ITK,hjmjohnson/ITK,hjmjohnson/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,thewtex/ITK,BRAINSia/ITK,vfonov/ITK,BRAINSia/ITK,LucasGandel/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,malaterre/ITK,LucasGandel/ITK,thewtex/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,Kitware/ITK,thewtex/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,Kitware/ITK,hjmjohnson/ITK,richardbeare/ITK,vfonov/ITK,Kitware/ITK,malaterre/ITK,richardbeare/ITK,LucasGandel/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,vfonov/ITK,thewtex/ITK,malaterre/ITK,BRAINSia/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,hjmjohnson/ITK,hjmjohnson/ITK,richardbeare/ITK,LucasGandel/ITK,LucasGandel/ITK,vfonov/ITK,vfonov/ITK,Kitware/ITK,BRAINSia/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,LucasGandel/ITK,vfonov/ITK,richardbeare/ITK,richardbeare/ITK,malaterre/ITK,malaterre/ITK,Kitware/ITK,thewtex/ITK,richardbeare/ITK,vfonov/ITK