Do call 'interpolate' when taking initial iterate from a file

In the code that takes the initial iterate from a while, a call
to 'interpolate' was out-commented, because interpolating an
'EmbeddedGlobalGFEFunction' was not possible back in the days.

That has changed so, and 'interpolate' can now be called.
I still doubt that the code ever worked or works now.
How could it ever be tested?

'#	geändert:       src/cosserat-continuum.cc