Project Pampa request: show curves for node grupps

It was not implemented in anim filter yet.

it's strictly speaking not so much clear how
"selected only" mode is expected to work when
having multiple node trees editing at the same
time. For now all the animation data from
selected group will be displayed.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60873 954f8c5b-7b00-dc11-b283-0030488c597c