Define color palette for plots

[mcauer]

Colors currently used in ohsome dashboard:

[mcauer]

Examples: 1) all colors like in css framework, 2) colors from plotly (green, red) mixed with yellow from css framework

[matthiasschaub]

After discussion, let's stick to what dashboard css theme provides. @mcauer will add a list of colors and their hexcodes to this issue.

[mcauer]

These are the default colors of the Sematic UI CSS Framework:

/*---  Colors  ---*/
@red              : #DB2828;
@orange           : #F2711C;
@yellow           : #FBBD08;
@olive            : #B5CC18;
@green            : #21BA45;
@teal             : #00B5AD;
@blue             : #2185D0;
@violet           : #6435C9;
@purple           : #A333C8;
@pink             : #E03997;
@brown            : #A5673F;
@grey             : #767676;
@black            : #1B1C1D;

So for the currentness indicator we need:

@red : #DB2828;

@yellow : #FBBD08;

@green : #21BA45;