Fix todo tags

[ll-nick]

Here's a list of all todo tags in the current code base. Let's fix them.

• arbitration_graphs/include/arbitration_graphs/arbitrator.hpp

  Line 44 in 7f2046a

  * \todo explain why it is a subclass of arbitrator

• arbitration_graphs/include/arbitration_graphs/arbitrator.hpp

  Line 45 in 7f2046a

  * \todo explain flags implementation and usage

• arbitration_graphs/include/arbitration_graphs/arbitrator.hpp

  Line 61 in 7f2046a

  //! \todo document why we need this

• arbitration_graphs/test/cost_arbitrator.cpp

  Line 93 in 7f2046a

  //! \todo This should be 0, if we estimate costs without calling getCommand (and thus gain/loseControl, see c2b2a93)

• arbitration_graphs/test/cost_arbitrator.cpp

  Line 97 in 7f2046a

  //! \todo This should be 1, if we estimate costs without calling getCommand (and thus gain/loseControl, see c2b2a93)

• arbitration_graphs/test/cost_arbitrator.cpp

  Line 105 in 7f2046a

  //! \todo This should be 0, if we estimate costs without calling getCommand (and thus gain/loseControl, see c2b2a93)

• arbitration_graphs/test/cost_arbitrator.cpp

  Line 108 in 7f2046a

  //! \todo This should be 0, if we estimate costs without calling getCommand (and thus gain/loseControl, see c2b2a93)