STYLE: Remove virtual from 19 TransformBase member functions
STYLE: Remove virtual from 19 TransformBase member functions

The `virtual` keyword should only be used for member functions that are meant to be overridden in a derived class.

See also C++ Core Guidelines (August 3, 2020), "C.132: Don't make a function virtual without reason", https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-virtual

SuperElastix/elastix,SuperElastix/elastix,SuperElastix/elastix,SuperElastix/elastix,SuperElastix/elastix