Style: Cleanups, added headers, renamed files

Made sure files in core/ and tools/ have a proper Godot license header
when written by us. Also renamed aabb.{cpp,h} and object_type_db.{cpp,h}
to rect3.{cpp,h} and class_db.{cpp,h} respectively.

Also added a proper header to core/io/base64.{c,h} after clarifying
the licensing with the original author (public domain).

core/math/a_star.cpp

@@ -1,5 +1,5 @@
 /*************************************************************************/
-/*  a_star.cpp                                                        */
+/*  a_star.cpp                                                           */
 /*************************************************************************/
 /*                       This file is part of:                           */
 /*                           GODOT ENGINE                                */

core/math/bsp_tree.h

@@ -30,7 +30,7 @@
 #define BSP_TREE_H
 
 #include "plane.h"
-#include "aabb.h"
+#include "rect3.h"
 #include "face3.h"
 #include "vector.h"
 #include "dvector.h"

core/math/face3.h

@@ -31,7 +31,7 @@
 
 #include "vector3.h"
 #include "plane.h"
-#include "aabb.h"
+#include "rect3.h"
 #include "transform.h"
 
 class Face3 {

core/math/octree.h

@@ -30,7 +30,7 @@
 #define OCTREE_H
 
 #include "vector3.h"
-#include "aabb.h"
+#include "rect3.h"
 #include "list.h"
 #include "variant.h"
 #include "map.h"

core/math/quick_hull.h

@@ -29,7 +29,7 @@
 #ifndef QUICK_HULL_H
 #define QUICK_HULL_H
 
-#include "aabb.h"
+#include "rect3.h"
 #include "set.h"
 #include "list.h"
 #include "geometry.h"

core/math/rect3.cpp

@@ -1,5 +1,5 @@
 /*************************************************************************/
-/*  aabb.cpp                                                             */
+/*  rect3.cpp                                                            */
 /*************************************************************************/
 /*                       This file is part of:                           */
 /*                           GODOT ENGINE                                */
@@ -26,7 +26,7 @@
 /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
-#include "aabb.h"
+#include "rect3.h"
 
 #include "print_string.h"
 

core/math/rect3.h

@@ -1,5 +1,5 @@
 /*************************************************************************/
-/*  aabb.h                                                               */
+/*  rect3.h                                                              */
 /*************************************************************************/
 /*                       This file is part of:                           */
 /*                           GODOT ENGINE                                */

core/math/transform.h

@@ -31,7 +31,7 @@
 
 #include "matrix3.h"
 #include "plane.h"
-#include "aabb.h"
+#include "rect3.h"
 /**
 	@author Juan Linietsky <reduzio@gmail.com>
 */