[Sources.List] Multiple variables used incorrectly for "selection enabled" state

[prl]

[Sources.List]

__selectionEnabled is initialised in __init__() and returned by the selectionEnabled property, but __selection_enabled is changed in setSelectionEnabled().

There doesn't seem to be a good reason why Sources.List has its own state for "selection enabled" rather than deferring to its master's "selection enabled" state.

[Peter Urbanec]

Fix Bug #575: [Sources.List] Multiple variables used incorrectly for "selection enabled" state

[Sources.List]

Change getSelectionEnabled() and the "index" property to defer to the source's master for the "selection enabled" state instead of using a local state (incorrectly).

→ <<cset a4210e99dbbf>>