added moving window structure, not yet done. added timestame sync for images and features detected

include/msckf_vio/feature.hpp

@@ -144,6 +144,8 @@ struct Feature {
     Eigen::aligned_allocator<
       std::pair<const StateIDType, Eigen::Vector4d> > > observations;
 
+  // NxN Patch of Anchor Image
+  std::vector<double> patch;
   // 3d postion of the feature in the world frame.
   Eigen::Vector3d position;