translate library:// folder paths on retrieval rather than when listing
CStdString -> std::string for CLibraryDirectory
Set the item path to the db path for filters
start directory may change after fetch, so update it to the items directory so that navigation out of the window via BACK works as expected
use the path in the items for testing paths after directory fetch
support for sources:// URLs for context menu, add source etc.
Merge pull request #3529 from jmarshallnz/library_urls_switch_on_fetch

Switch library:// URLs to 'real' URLs on fetch, rather than list