* Fixed a nasty bug which meant that it was impossible to set an active node. Was caused by ntreeCopyTree() getting called when compo updates were done and clearing the active flags. The active flag clearing is only really needed for the "internal_select" case which is only used for duplicating selected nodes (from Shift-D duplicate).
* Recoded click-selection code. Was a mess of old code, bad exceptions from the old code half ported, duplicate operators, unnecessary flags/modes.
* Fixed bug #19927: compositing node groups can't be access via "tab" or ungrouped via "alt+g". Was probably related to the active group not being able to be set.
* Made resizing nodes work again. Again, this was due to the active node bug.
* Made adding a new group with Ctrl-G correctly update the views
* Added 'active node' panel for the Nodes Editor. This panel, in the NKEY region, shows the settings for the active node. Included in this panel is a field used for editing the unique-name of the node too.
* Fixed a number of uninitialised vars warnings that I missed in previous commit...
This commit restores Grease Pencil functionality for the Nodes Editor. Grease Pencil data is now stored at the NodeTree level, which means that annotations remain with the NodeTree they were made for.
Possible TODO's:
* In future, it may be worth investigating attaching Grease Pencil data to individual nodes, to allow annotations to stay attached to nodes as they are moved
* Include the settings for the 'active node' in a panel in the new NKEY region where the Grease Pencil buttons appear.
