When presenting, use a slightly different setup

When the PRESENTING environment variable is set, use a slightly
different setup: wombat theme, matching mode-line, a few things
disabled.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Do not enable golden-ratio when presenting

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
gitignore: Ignore session files

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>