[Bf-committers] Nameable group node sockets and other improvements

[Lukas Tönne]

As part of the ongoing work on the particles-2010 branch i decided to
address some of the nagging issues of group nodes. While nice in
theory, the usability of node groups suffers from bad behavior and
missing features to reveal its true power. Three things in particular
i would like to fix:

* External sockets should be renameable to give some meaning to the
parameters and outputs of a complex group.
* The order of external socket should be changeable (e.g. to stress
different importance of sockets).
* The internal sockets that get an external counterpart should be
selectable explicitly, instead of having to use ugly workarounds to
hide some of them.

The first of these has now been implemented as a patch for trunk
(which i will port to the particles branch too of course). It seems to
work very well, but since i had to change some of the inner workings
of group nodes, it could use some more testers. See the patch
description for details.

https://projects.blender.org/tracker/index.php?func=detail&aid=24883&group_id=9&atid=127

There are certainly more features that would be nice to have for nodes
(nested groups, more ui improvements), but these three can be
implemented quickly.

Cheers,
Lukas Tönne