Support Alternate Map Sources #57

Is your feature request related to a problem? Please describe.
Apple Maps don't always have all of the features, such as address labels on the map

Describe the solution you'd like
A way to add additional maps when showing the map display

Additional context
Map sources are typically XML files that have the tileserver and other pertinent information. An example one for Google Maps is:

<?xml version="1.0" encoding="UTF-8"?>
<customMapSource>
	<name>0.GoogleHybrid</name>
	<minZoom>0</minZoom>
	<maxZoom>21</maxZoom>
	<tileType>png</tileType>
	<tileUpdate>None</tileUpdate>
	<url>https://mt.google.com/vt/lyrs=y,hl=en&amp;x={$x}&amp;y={$y}&amp;z={$z}</url>
	<backgroundColor>#000000</backgroundColor>
</customMapSource>