QwtSpline::bezierControlPoints added


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1937 29e17f8d-cf37-471e-a288-72cc03a76eda
QwtSpline::polygonP added


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1938 29e17f8d-cf37-471e-a288-72cc03a76eda
check of borderPath invokable added to avoid Qt warnings


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1940 29e17f8d-cf37-471e-a288-72cc03a76eda