corrected one error in Interpolationparameters

git-svn-id: svn://svn.code.sf.net/p/vcg/code/trunk/vcglib@5497 e8973e21-934d-0410-ac44-de4585f5606d
included missing header.

git-svn-id: svn://svn.code.sf.net/p/vcg/code/trunk/vcglib@5498 e8973e21-934d-0410-ac44-de4585f5606d