Make python_qt_binding standalone

[130s]

I just don't know why it has to depend on catkin & rosbuild. If it is not necessary we can make it separate from ROS. I think it would be useful especially after having looked at PySide that doesn't handle .ui file well.

[130s]

According to @dirk-thomas, catkin is currently used for installing 3rd party packages, but once REP136 finalizes python_qt_binding can become ROS-agnostic.

I set milestone to Hydro release.

[dirk-thomas]

@wjwwood fyi

[130s]

Btw, the fact that python_qt_binding depends on ROS blocks the following idea in concept making mtg, since qt_gui_core depends on python_qt_binding.

The core framework of ROS GUI depends only on rospkg (not ROS) 

This idea maybe invalid since it's too old and probably not a part of the official review process, but at least there's another open ticket link that suggests to make some modules in rqt framework standalone and I thought it's worth noting.

[dirk-thomas]

With the pull request #5 the package can be released and used as a standalone Python package. But for ROS it will still be released as a catkin package. The rosbuild dependency is required so that dry packages can access the CMake helpers.

[130s]

@dirk-thomas this is great! I've also seen it released into PyPi. With this I can make my python qt GUIs that both non-ROS and ROS users use truly compatible.

Where is it going to be documented? PyPi points to ros wiki but I've seen ROS-agnostic pkgs tend to be documented somewhere else? I'm willing to contribute to its usage if you like.

[dirk-thomas]

I think it would make most sense to add some documentation into a doc folder in this repo. Please feel free to send pull request which describe how to use this package. Any contribution - especially for documentation - is highly appreciated.