ENH: Write temporary test files to the build directory
ENH: Write temporary test files to the build directory

This avoids polluting the source directory.

kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix