Bug#804575: [Debian-med-packaging] Bug#804575: insighttoolkit4: build-depends on libdcmtk2-dev which is no longer built

[Gert Wollny]

I'll take on this bug once gdcm (=2.6) - another build dependency of
insighttoolkit4 - has cleared NEW. 

I.e. in the packaging svn I already changed the dependency. 

Best, 
Gert