Node options draw function fix for C nodes: use the default button draw function as a fallback if no extended draw function is defined.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57104 954f8c5b-7b00-dc11-b283-0030488c597c
Replacement for the "Active Node" panel in node editor properties sidebar. This panel is now defined in space_node.py instead of node_buttons.c. The properties have been split up into generic properties
(name, label), custom colors (closed by default) and input parameters (extra options + unlinked input socket values).

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57105 954f8c5b-7b00-dc11-b283-0030488c597c