Add ability to configure map style in layout xml

[KyleGW]

This allows the ability to have different pre-configured styles without having to specify on command line every time.

If done at a widget level it could enable the ability to have two maps on the overlay with different styles. I had an idea to try to make a 'debug' overlay that would have multiple different map styles and zoom levels that I could evaluate what works best for a given video, and then realized the limitation by having it on the command line.

<component type="journey_map" name="journey_map" size="512" corner_radius="35" opacity="0.95" style="osm-bright"/>
<component type="moving_journey_map" name="moving_map" size="512" zoom="17" style="tf-transport-dark"/>

[time4tea]

Hiya - Thanks for the suggestion! - I did try to abstract the map style from the the config on purpose, to avoid making styles in the xml config. This means that a particular xml config can be rendered with any map style. However, I do see that having multiple map styles in a single render could potentially be useful.. but i haven't had a "killer" reason to do that. A "debug" layout isn't quite a strong enough reason, I don't think. If there was a non-debug reason... Perhaps your debug thing could alternatively be easily scripted externally? for style in a b c d; do; venv/bin/gopro-dashboard.py --map-style $style...