Feature/inlined wireframe

This PR is quite big but should be compatible (at least in terms of functionality) with current code.
The PR splits the OpenGL ES scene graph processing from the `osgjs` plugin and adds the `gles` plugin. So when creating an osgjs file you should add the `gles` plugin e.g. `osgconv my_input.obj.gles my_output.osgjs`.
It adds 
* some control option over triangle strip generation (`triStripMinSize`, `allowDrawArrays`)
* the possibility to generate wireframe data in the same scene graph as solid data using `enableWireframe=inline`
* indexes lines
* possibility to dump some specific buffer into a specific file (based on user values)
* updates user values  serialization