Data Sources: Right-click on XY Data or blank space causes error

[Fabian Thiel]

Right-clicking on Raster Data, Vector Data causes python error:

2018-10-31T15:15:49     WARNING    Traceback (most recent call last):
              File "C:/Users/ThinkPad/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\enmapboxplugin\enmapbox\gui\datasourcemanager.py", line 1339, in createContextMenu
              if isinstance(src, DataSourceSpectralLibrary):
             UnboundLocalError: local variable 'src' referenced before assignment

[Benjamin Jakimow]

fixed issue #207

→ <<cset 9c9ab76c7f5f>>