Blender Git Loki

Nla Strip Controls: Added dedicated "Expander" channel to Action/Graph Editors

The "Nla Strip Controls" channel is used to house the per-strip
FCurves for controlling the strip_time and influence properties.
It sits above the active action's first group, at the same level
in the hierarchy as other groups.

TODO: It looks like a dedicated FCurve channel is needed for these
control FCurves, so that we won't accidentally apply NLA mapping
or have these FCurves disabled by the path lookups failing.