icolor maps again


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2093 29e17f8d-cf37-471e-a288-72cc03a76eda
spectrogram example improved


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2094 29e17f8d-cf37-471e-a288-72cc03a76eda
hue color map using a precalculated rgb table


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2096 29e17f8d-cf37-471e-a288-72cc03a76eda