Fixed update_drupal_project function: updates were mostly broken because of no git pull, now also supports reverting patches before updating.
Implemented one of the two remaining TODO: make it easy to deal with Development/Testing/Acceptance/Production environments.
Renamed set_drupal_permissions to drupal_set_permissions; cleaned it up; use function arguments instead of environment variables.

Also expanded the example to show (DTAP) environment-specific settings.
Added drupal_rm_unnecessary_txt function that removes all .txt files from the Drupal root except for robots.txt.
Minor comment improvements and function name consistency improvements.
dash compatibility for the DTAP example.
README expanded to cover DTAP handling.