[Bf-funboard] Add "Blend from shape" and "Shape propagate" operators for curves

[Arnaud Couturier]

Hello,

this is the first time I post to this mailing-list.
I read we can propose and request Blender features here, so here I am. But
I'm not sure if any active Blender dev is actually reading what's posted..
anyway.

When working with shape keys for MESHES, we have the options "Blend from
shape" and "Shape propagate", which are very useful.

But there are no such features for shape keys for CURVES. For instance if I
make a mistake in a shape, and I want to revert a part of the curve to the
original Basis" shape, I can't. That's annoying, forcing me to basically
erase the key, and do it again. No mistake is tolerated.

Is there a reason such basic features are missing for curves?
Can anyone see if that can be added in Blender at some point?

I'm on Blender 2.78a, the latest at this time.
Thank you!
Arnaud