added some more tests

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402980

dlib/test/geometry.cpp

@@ -283,6 +283,11 @@ namespace
 
             DLIB_TEST(rotate_point(center, p1, pi/4) == point(8,8));
             DLIB_TEST(rotate_point(center, p1, -pi/4) == point(8,-2));
+
+            DLIB_TEST(rotate_point(center, p1, pi/4 + 10*pi) == point(8,8));
+            DLIB_TEST(rotate_point(center, p1, -pi/4 + 10*pi) == point(8,-2));
+            DLIB_TEST(rotate_point(center, p1, pi/4 - 10*pi) == point(8,8));
+            DLIB_TEST(rotate_point(center, p1, -pi/4 - 10*pi) == point(8,-2));
         }
 
     }