#1 bugfix for shareitemmodel/treeview

[vvvrrooomm]

this fixes:
-delete the actually clickes share, not the last selected
-don't crash when right click (and select remove) on empty space in the treeview
-infinite expandale entries, though this can be improved in various directions: either use listview or make expansion sensible by adding useful information

this does not fix:
-crash when selecting remove on the filler message "click or drag to add"

[vvvrrooomm]

patch