Changed scrollWheel to use precise scrolling deltas when available.

Use precise scrolling deltas only on supported versions of OS X;
hasPreciseScrollingDeltas, scrollingDeltaX, scrollingDeltaY are
available in OS X v10.7 and later.
Replaced a single occurence of a tab character with 4 spaces for
consistency in src/socoa_window.m.

README.md

@@ -112,6 +112,7 @@ See the [GLFW documentation](http://www.glfw.org/docs/latest/).
                    returned by `glfwGetProcAddress`
  - [Win32] Bugfix: The user32 and dwmapi module handles were not freed on
                    library termination
+ - [Cocoa] Changed scroll callback to use precise scrolling deltas when available
  - [Cocoa] Enabled explicit creation of OpenGL 3.x and 4.x contexts as supported
            by OS X 10.9
  - [Cocoa] Bugfix: The clipboard string was not freed on terminate

src/cocoa_window.m

@@ -606,8 +606,27 @@ static int translateKey(unsigned int key)
 
 - (void)scrollWheel:(NSEvent *)event
 {
-    double deltaX = [event deltaX];
-    double deltaY = [event deltaY];
+    double deltaX, deltaY;
+
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
+    if ([event respondsToSelector:@selector(hasPreciseScrollingDeltas:)])
+    {
+        deltaX = [event scrollingDeltaX];
+        deltaY = [event scrollingDeltaY];
+
+        if ([event hasPreciseScrollingDeltas])
+        {
+            deltaX *= 0.1;
+            deltaY *= 0.1;
+        }
+    }
+    else
+#else
+    {
+        deltaX = [event deltaX];
+        deltaY = [event deltaY];
+    }
+#endif /*MAC_OS_X_VERSION_MAX_ALLOWED*/
 
     if (fabs(deltaX) > 0.0 || fabs(deltaY) > 0.0)
         _glfwInputScroll(window, deltaX, deltaY);