Revert "Added IKTYPE_TRANSFORM_6D definition to solve issue #5"

This reverts commit 041a914db4a6a063749c6b65946061fc6692166e. As explained in
the issue #5 comments, the #define should be inserted into the generated code
(either by the generator script or manually), *not* set to one arbitrary
value for all users. That would silently break the generated code for all
others.