ocioview: Curve Inspector improvements

[michdolan]

• Move README.md to root app folder.
• Change curve inspector grid to always render as a square with 10 segments. This improves log and inverse transform curve rendering consistency.
• Add transform init callback to set new transform subscriptions to the current viewer if set to passthrough. This reduces the current two clicks to get a transform connected to a viewer to one click if the viewer is not currently subscribed to a transform.

ACEScc, linear scale:

ACEScc, log scale:

ACEScc, linear scale, inverse:

ACEScc, log scale, inverse:

[doug-walker]

@michdolan, this PR has been approved. Is there anything else you wanted to add, or should we go ahead and merge it?