ColorBarLegend component as submodule

[forman]

ColorBarLegend component is now implemented in its own submodule.

At the same time it shall serve as a template for the decomposition many of the other large components such as SettingsDialog, UserPlacesDialog, Viewer, TimeSeriesChart, and a few more.

Template:

src/components/Component/
    index.tsx              // makes it a module and exports main component
    Component.tsx          // the main component
    SubComponent1.tsx
    SubComponent2.tsx
    ...
    SubComponentN.tsx