set paper size for latex to a4
add gitignore file
add main chapter of the course
add skeleton for data types and introduction

the 2 files contain only the main sections
remove underscore in title
add skeleton file for Object References chapter
change name of rst files to manipulate them easily on unix

replace space in rst files by _
and change index.rst according to this renaming
add skeleton files
fix spelling in subsection
add some examples of rest/sphinx  capabilities