integer arithmetic for hue color map


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2082 29e17f8d-cf37-471e-a288-72cc03a76eda
hue color map performance improved


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2083 29e17f8d-cf37-471e-a288-72cc03a76eda
color maps again


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2084 29e17f8d-cf37-471e-a288-72cc03a76eda
spectrogram example improved with different color maps


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2089 29e17f8d-cf37-471e-a288-72cc03a76eda
drawing of color bars with semi transparent colors fixed


git-svn-id: svn://svn.code.sf.net/p/qwt/code/trunk@2091 29e17f8d-cf37-471e-a288-72cc03a76eda