(Enhancement) Selecting recursive parent node as independent values

[lyoum]

Currently, the library does support allowParentSelection=true and multiple=true, but does not support option of selecting 1st level node as value with 2nd level node as value, together as multiple selection.

Example, once I select 2nd level value "Disco", I cannot select 1st level value "Folk Music" as value, although ticked:

But the actual value selected is only "Disco".

Probably needs a new option named something like allowIndependentValues