spline curve fitter classes moved to qwt_spline_curve_fitter


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1836 29e17f8d-cf37-471e-a288-72cc03a76eda
bezier spline interpolation improved ( no more limitation for ordered x
values )


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1837 29e17f8d-cf37-471e-a288-72cc03a76eda
using spline interpolated curves


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1838 29e17f8d-cf37-471e-a288-72cc03a76eda
some code added using QPainterPath::cubicTo as spline fitter


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@1839 29e17f8d-cf37-471e-a288-72cc03a76eda