Enum's Defined in Msgs

[Dave Kotfis]

In many places (e.g. ihmc_msgs/FootstepStatusMessage), enums are defined in comments. ROS msgs can define enum's directly so that they can be used in code (see visualization_msgs/Marker for an example). This would allow us to ensure that our code is automatically updated if the enum values change.

[Georg Wiedebach]

Thanks for the suggestion - the message files are updated accordingly on the development branch.