Hiding the legend if there's no proper legend to be found.
Updated changelog
Fixed icon before graph title
updated changelog
Indentation
Properly implemented symbol_url so that the workspaceitem also has an icon
Added test for empty legend.

Added missing location_annotations() to the datasource as the lack of it
caused failing tests. So now the tests function again, but the
legend-is-not-empty test fails still. It needs more mocking (it needs
annotations), but I would really have to dive into the code and @remcogerlich
can probably add it much quicker.
Merge pull request #3 from lizardsystem/reinout-legend-hiding

Hide the legend when unavailable + fix graph icon