Implemented message filters for ensuring transform availability. Also did some small code cleanup for safely obtaining transforms.
Implemented message filters for ensuring transform availability. Also did some small code cleanup for safely obtaining transforms.

ayrton04/robot_localization,adnanademovic/robot_localization,braincorp/robot_localization,tscho1l/robot_localization,braincorp/robot_localization,punithm/robot_localization,adnanademovic/robot_localization,tscho1l/robot_localization,ayrton04/robot_localization,punithm/robot_localization