Remove todo-example; Add more examples; Refactor

A lot of small changes here:

- I removed all references to old TODO-example code
- I added more robot examples: Twice the same dummy example in two different files, one Selenium-example taking a screenshot of Google.com and inserting the result into resulting documentation (this requires installing robotframework-selenium2libary into virtualenv)

After I added more examples, it was quite clear that robot.run for .rst-file does not work reliable. It seems to execute every other test and fail the rest. The errors look like they may also have side effects for the actual Sphinx-build.

So, I continued on the path of duplicating parser code from new restreader.py.

Also a few other changes:
- The temporary file is now created into the directory of the original source file: this allows Robot Framework to find correctly possible referenced resoures (example of that in third_example.rst)
- robot.run get a few parameters to 1) save output screenshots into directory of the source (so that .. image:: -directive can find them) 2) disable creation of output.xml, log.html and report.html

Next:
- Try to add a custom directive for disabling the sphinx-run per document (the global setting works now correctly)