New: Hotkey/menu access in 3D window to add constraints. Works in PoseMode

as well as for Objects. Hotkey: CTRL+ALT+C (bit clumsy I know, but I like
to use the Ckey).

Constraints are added to the active Object or Bone.
Based on selection context, the menu has three versions:

Pose Mode:
  - if another bone is selected, bone becomes target
  - else if another Object is selected, Object becomes target
  - else it adds a new Empty as target
Object Mode
  - if another Object is selected: Object becomes target
  - else it adds a new Empty as target

Same works this way now for CTRL+I, "Add IK".

To be solved: ALT+C in PoseMode is "Clear Constraints", but in Object Mode
it does "Convert" still...

source/blender/src/space.c

@@ -87,6 +87,7 @@
 #include "BIF_drawtext.h"
 #include "BIF_drawscript.h"
 #include "BIF_editarmature.h"
+#include "BIF_editconstraint.h"
 #include "BIF_editfont.h"
 #include "BIF_editkey.h"
 #include "BIF_editlattice.h"
@@ -1157,6 +1158,8 @@ static void winqreadview3dspace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 					else
 						convertmenu();	/* editobject.c */
 				}
+				else if(G.qual==(LR_ALTKEY|LR_CTRLKEY)) 
+					add_constraint(0);	/* editconstraint.c, generic for objects and posemode */
 				else if((G.qual==LR_SHIFTKEY)) {
 					view3d_home(1);
 					curs= give_cursor();