Use M_MARGE_VALUE instead of 99999.0f

Source/Urho3D/UI/UI.cpp

@@ -95,7 +95,7 @@ UI::UI(Context* context) :
     dragBeginDistance_(DEFAULT_DRAGBEGIN_DISTANCE),
     mouseButtons_(0),
     lastMouseButtons_(0),
-    maxDoubleClickDist_(99999.0f),	
+    maxDoubleClickDist_(M_LARGE_VALUE),
     qualifiers_(0),
     maxFontTextureSize_(DEFAULT_FONT_TEXTURE_MAX_SIZE),
     initialized_(false),