Generate cases legend CSS dynamically

[elchininet]

This pull request refactors the repetitive code to generate the colors of the cases-legend and creates a function to generate them dynamically.

So, this:

$('#cases1').css(
    'color',
    'rgba(176,30,34,' +
        logx(factor, (genInfo.max_pros * factor * 0.2) / genInfo.max_pros) +
    ')'
);
$('#cases2').css(
    'color',
    'rgba(176,30,34,' +
        logx(factor, (genInfo.max_pros * factor * 0.4) / genInfo.max_pros) +
    ')'
);
$('#cases3').css(
    'color',
    'rgba(176,30,34,' +
        logx(factor, (genInfo.max_pros * factor * 0.6) / genInfo.max_pros) +
    ')'
);
$('#cases4').css(
    'color',
    'rgba(176,30,34,' +
        logx(factor, (genInfo.max_pros * factor * 0.8) / genInfo.max_pros) +
    ')'
);
$('#cases5').css(
    'color',
    'rgba(176,30,34,' +
        logx(factor, (genInfo.max_pros * factor) / genInfo.max_pros) +
    ')'
);
$('#cases').html(genInfo.max_pros);

Can be replaced by this:

updateCasesLegendCSS(factor, genInfo.max_pros);