Reorganized core/ directory, it was too fatty already

-Removed FuncRef, since Callable makes it obsolete
-Removed int_types.h as its obsolete in c++11+
-Changed color names code

core/math/camera_matrix.cpp

@@ -31,7 +31,7 @@
 #include "camera_matrix.h"
 
 #include "core/math/math_funcs.h"
-#include "core/print_string.h"
+#include "core/string/print_string.h"
 
 float CameraMatrix::determinant() const {
 	return matrix[0][3] * matrix[1][2] * matrix[2][1] * matrix[3][0] - matrix[0][2] * matrix[1][3] * matrix[2][1] * matrix[3][0] -