Blender Git Loki

Merge branch 'master' into node-group-single-socket-nodes

Hide new group input sockets by default.

Merge branch 'master' into node-group-single-socket-nodes

Disable the virtual group extension socket by default.

Merge branch 'master' into node-group-single-socket-nodes

Show group output nodes with all sockets.

Merge remote-tracking branch 'origin/node-group-single-socket-nodes' into node-group-single-socket-nodes

Merge branch 'master' into node-group-single-socket-nodes

Merge branch 'master' into node-group-single-socket-nodes

Single-socket input/output nodes in node groups.

Changes the default group input/output nodes in groups to show only
a single socket. This is more convenient for keeping connections short
and put parameters closer to where they are used inside a group.

For input nodes this is purely a UI feature: they can already be
duplicated and unused sockets can be hidden (ctrl+h). The patch only
makes this the default setup of input nodes by providing all inputs
separately in the "Add Node" menu.

For output nodes the situation requires some functional changes,
because outputs have to be unique.

The "virtual" extension socket on group input/output nodes is now
disabled by default, since it adds a lot of visual noise without saving
much work (see discussion in T68733). The feature can be enabled with
a per-node flag.

Todo:
- [ ] Implement unique output handling across different node systems.

Differential Revision: https://developer.blender.org/D11853

Flag for group nodes to disable extension socket.

Sanity checks for the extension socket in groups.

Add single-socket input/output nodes in groups.

Simplify group node extension handler function.

Use a common function for handling the "extension" socket in group
input/output nodes.