Store sketch in armature instead of ugly global.

Like edit data, this isn't saved, just a temp pointer used during work session.

Also bring back sketching panel for 3d view.

source/blender/windowmanager/intern/wm_init_exit.c

@@ -208,7 +208,6 @@ void WM_exit(bContext *C)
 //	BIF_GlobalReebFree();
 //	BIF_freeRetarget();
 	BIF_freeTemplates(C);
-	BIF_freeSketch(C);
 	
 	free_ttfont(); /* bke_font.h */