Blender 2.73 release candidate commit

This commit contains:

- Subversion bump to 2.73
- Release cycle is set to "rc"
- Submodules are pointed to appropriate tag now
  (addons contrib just points to the latest contrib repo)
- New shiny splash screen!

source/blender/blenkernel/BKE_blender.h

@@ -41,8 +41,8 @@ extern "C" {
 /* these lines are grep'd, watch out for our not-so-awesome regex
  * and keep comment above the defines.
  * Use STRINGIFY() rather than defining with quotes */
-#define BLENDER_VERSION         272
-#define BLENDER_SUBVERSION      3
+#define BLENDER_VERSION         273
+#define BLENDER_SUBVERSION      0
 /* 262 was the last editmesh release but it has compatibility code for bmesh data */
 #define BLENDER_MINVERSION      270
 #define BLENDER_MINSUBVERSION   5
@@ -51,7 +51,7 @@ extern "C" {
 /* can be left blank, otherwise a,b,c... etc with no quotes */
 #define BLENDER_VERSION_CHAR   
 /* alpha/beta/rc/release, docs use this */
-#define BLENDER_VERSION_CYCLE   alpha
+#define BLENDER_VERSION_CYCLE   rc
 
 extern char versionstr[]; /* from blender.c */