concerning index, you can't really distinguish betwen type and name, so draw index accordingly
added -p/--print-only option
improved 'man page', mainly the DESCRIPTION
cosmetic changes

mostly breaking lines before the 80th column
added new ideas to todo list
now prints usage in case of invalid options and learned the option --help
learned the -i,--image-only option
extended TODO list
--help now prints to stdout instead wronly stderr
cosmetic change: print_usage... now uses <<EOF instead multiple 'echo "...'
exended usage by refering to the primary doc which is the git-draw script itself