assign contrasted colors TimeLine radio chanel events

[alexrayne]

Old colors table for radio-chanels has many colors that are non-distinguish by eye. Therefore, if your chanels not luck, you can get coloring by similar colors.

For example: chanel 15 - color:404040 - is not distingush from chanel 26 color:404000

This patch provide colors of radio-chanel are perefered high-contrasted first, from a set of about 10 colors that are good distinguish.

This selection is still a bit robust. When luck of contrast colors, there selects color from old colors set.