This allows you to set and animate the values of socket inputs and outputs, for example the value node.
It's also a step on the way to manipulating node trees via python (i.e. linking node sockets to each other).
This fixes [#19841] RGB Node in compositor not working
*Put the Modifiers tab *before* the ObData (mesh, curve etc) tab, because modifiers actually apply to Object , not the ObData, even though the opposite would appear to make more sense.
* Buttons header: made tab buttons bigger, remove view menu,
replaced by RMB menu in main region.
* Timeline header: tweak button placement and alignment, added
a play reverse icon.
* Window type chooser menu: removed audio and scripts windows,
change console and logic icons.
* Node space: disable the channel region until it is used.
* Context panel now draws without header, with arrows, no scene name.
* Softbody vertex group search popup.
* Improve names for autogenerated shortcut keys in menus.
* Make most Select menus in the 3D view header work.
* Fix armature border select selection syncing.
* Add POSE_OT_select_constraint_target,
MESH_OT_select_by_number_vertices, MESH_OT_select_vertex_path.
* Merge mesh select similar into one operator.
* Don't give MESH_OT_select_random Space hotkey.
* Add DAG_object_flush_update to many mesh edit tools, not calling this
will crash with modifiers.
* RNA_def_enum_funcs for dynamic enums in operators, but not very useful
without context yet.
* Fix refresh issue with image window header + editmode.
* Fix drawing of shadow mesh for image painting.
* Remove deprecated uiDefMenuButO and uiDefMenuSep functions.
* Remove keyval.c, code is in wm_keymap.c already.
* Rename WM_operator_redo to WM_operator_props_popup.
* Menu and header more complete now.
* Clean up Game Properties panel and moved View Properties panel
to python.
* Fix some drawing issues when combining tiles, repeat and aspect,
some also from 2.4x, these options didn't work together 100%.
* Moved proportional edit, snap, autokey mode, and a few others
from Scene to ToolSettings.
* RNA wrapped properties in ToolSettings for the UV editor:
proportional edit, snap settings, selection modes.
