Allow connections to be made by named input as well as index

[bbc]

Allow connections to be made by named input as well as index

[MatthewShotton]

Proposed connection rules.

• Named connections override connections made by index or connections made by just calling connect.
• After named connections resulting connections are filled in order by z-index.
• If Compositing nodes are connected by named input, it's treated the same as a regular connect call with no parameters.

var videoNode, imageNode,canvasNode, effectNode, compositingNode;

videoNode.connect(effectNode, "input_a");
imageNode.connect(effectNode, 2);
canvasNode.connect(effectNode,-1);

/* Resulting Mapping
* videoNode -> input_a
* canvasNode -> input_b
* imageNode -> input_c
*/

[MatthewShotton]

Added in commit 766ca62 .