Rename index file from indef.fr.txt to index.txt to dit Sphinx needs and adjusted conf file in consequence. Moved images from fr/ to book/ so that images would be in central location for both en and fr books.

This directory is where you should put your lax components.

For your application to actually use a component, you also 
have to modify the ``INCLUDED_COMPONENTS`` variable in 
the ``custom.py`` module.