Cleanup of UI for new renderpipeline

- removed "Unified" button, replaced with "HD" preset for 1920x1080 output
- removed the unused "Pass" options
- removed the unused "Strands" render-layer option

Because the internal render pipe supports this already; added two more
render-layer options:

- "Sky", to enable/disable sky render in a layer (this was part of "Solid"
  before, not so correct... to ensure previously saved files work, the
  "Sky" option is set by default when "Solid" was set. The version patching
  will do this temporally always, until we've bumped up version to 2.42
- "Edge", to enable/disable edge render in a layer. Nice for compositing.

Also in this commit: fixed warnings for exported functions for the new
Node Editor pull-down menus.

source/blender/src/editnode.c

@@ -1797,7 +1797,6 @@ static int node_uiDoBlocks(SpaceNode *snode, ListBase *lb, short event)
 void winqreadnodespace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 {
 	SpaceNode *snode= spacedata;
-	float dx;
 	unsigned short event= evt->event;
 	short val= evt->val, doredraw=0, fromlib= 0;