Functionality to support Gazebo

[Huckleberry Febbo]

@jdlangs from what I can tell, Gazebo is not supported because I get:

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 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release
|__/                   |  x86_64-pc-linux-gnu

julia> using RobotOS

julia> @rosimport gazebo_msgs.msg: ModelState

julia> ModelState()
ERROR: UndefVarError: ModelState not defined

julia> 

Is this correct? If so, would it be hard to add this functionality? It would be extremely helpful.

@stevengj I am assuming that it may be an upstream issue with the way PyCall,jl tries to import this. For instance in python this works fine:

>>> import rospy  
>>> import roslib
>>> from std_msgs.msg import String
>>> from gazebo_msgs.msg import ModelState
>>> ModelState()
model_name: ''
pose: 
  position: 
    x: 0.0
    y: 0.0
    z: 0.0
  orientation: 
    x: 0.0
    y: 0.0
    z: 0.0
    w: 0.0
twist: 
  linear: 
    x: 0.0
    y: 0.0
    z: 0.0
  angular: 
    x: 0.0
    y: 0.0
    z: 0.0
reference_frame: ''
>>> 

[Josh Langsfeld]

This is the same issue as in #27. You just didn't call the rostypegen function. It did find the gazebo ModelState message class without issue as there was no error thrown when you ran the @rosimport command.

[Huckleberry Febbo]

Thanks!