Add sci-libs/itk Closes: #124241

This is an ebuild for the Insight Toolkit v4.4.  I tested building it on amd64 with useflags  _fftw hdf5 itkv3compat python review shared -debug -examples -test_

repoman complains about:  
* sci-libs/itk/metadata.xml: Unknown herd "no-herd"

but I don't know what to put there (It's my first pull request for an ebuild). 

I happily work on improving it