PDF output: add custom LaTeX stylesheet

- add custom stylesheet
- add wallpaper package
- set title colors
- prevent images from floating
- set lower font size for code snippets
- remove blank pages between chapters
- remove empty LaTeX date command

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
Readme: remove comment about PDF output

PDF layout is now satisfactory.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
sed : modifiez votre texte sans ouvrir vos fichiers: shorten commands

Use variables to shorten command line instructions to enhance PDF output.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
Tester les produits pour les documenter: change image print size

Change image print size to better display in PDF.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
Configuration: switch to version 1.3

Change release in conf.py.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>