Synchronize cmake submodule.
Add step by step planning to ProblemSolver class
Check if a path exists in ProblemSolver::finishSolveStepByStep
Reset problem when robot is loaded, not when calling ProblemSolver::solve

  Formerly, until calling method solve, additional obstacles where not taken
  into account.
Cosmetic changes

  - re-indent files before inserting directed roadmap,
  - delete trailing white spaces.
Make possible to use no path optimizer.
Move test of existence of a path from PathPlanner to Roadmap.
Implement oriented roadmap

  - new implementation of connected components.
Move graph-connected-component.hh to src.

  User do not need this class.
Rename CCGraph -> ConnectedComponentGraph.
Simplify insertion at end of list.
Add methods to simplify management of connected component,

  - when creating a new node and connecting it both ways to another node, the
    new node is simply added to the connected component of the previously
    existing one.
Make solver methods virtual in class ProblemSolver
Add protected method to set the problem and the roadmap.
Merge remote-tracking branch 'origin/master' into topic_plan_step_by_step