Added the Composer class.

A totally separate composer class. It uses manager and slam objects
to compose an upto date poses. The data assembler runs in a separate thread.

There are separate threads for publishs a) trajectories b) latest camera pose
c) loop edges d) disjointset status image. All these are made efficient.
now the cpu usage (load-average on desktop) does not exceed 2.5 (for vins+cerebro+pose graph solver).

TODO:
- inter-loopedges  and intra-loopedges in separate colors
- get cam_T_imu
- publish at 100 hz in imu frame of ref

Author: mpkuse

CMakeLists.txt

@@ -70,6 +70,7 @@ add_executable( keyframe_pose_graph_slam
         src/utils/RosMarkerUtils.cpp
         src/utils/RawFileIO.cpp
         src/Worlds.cpp
+        src/Composer.cpp
         )