add dynamic_reconfigure to line_detector

[bsubei]

we need to be able to change parameters like Hough or Histogram stuff on the fly using dynamic_reconfigure (instead of having a separate GUI program with sliders for the parameters). That GUI program won't work when we have multiple algorithms.

[bsubei]

doing this in this node will make it so much easier to make it work for the other line_detection nodes we make (for the other algorithms). If we make the current line_detection node good enough and complete, we'll just clone it and modify the algorithm.

[bsubei]

this obviously means I first need to implement a ROS parameter server (which I didn't do yet)

[bsubei]

Helpful links:

https://github.com/UCSD-E4E/stingray-auv/wiki/Writing-publisher-subscriber-with-dynamic-reconfigure-and-parameter-server-(python)

http://library.isr.ist.utl.pt/docs/roswiki/dynamic_reconfigure(2f)Tutorials(2f)SettingUpDynamicReconfigureForANode(28)python(29).html

http://wiki.ros.org/rospy/Overview/Parameter%20Server

[bsubei]

This tutorial goes over setting up dynamic reconfig for a python node (groovy distro, hope this works on indigo) http://wiki.ros.org/dynamic_reconfigure/Tutorials/SettingUpDynamicReconfigureForANode(python)

[bsubei]

so, to be precise, what needs to be done is to create a cfg file for the parameters to be changed, and then rewrite the line_detection nodes to be dynamic_reconfigure servers (so they can listen to rqt_reconfigure that sends params).

[bsubei]

also, it's important to note that we want to implement dynamic_reconfigure as opposed to rosparam, because rosparam is not meant for parameters that change.

http://wiki.ros.org/ROS/Patterns/Parameterization

[bsubei]

this feature introduced a bug, where the parameters that are dynamically changed are not validated before being plugged in to opencv. Check issue #25

[bsubei]

also, abandoning rosparam branch (no need for rosparam if we use dynamic_reconfigure)