Fixed "gbdm" function so that only locally merged branches are
deleted.

- Prompt per branch as been removed.
- Remote branches are no longer considered.
Added "gamendh" alias for ammending current changes to HEAD.

- Amends all uncommitted and un-staged changes to last commit,
  reusing last commit's message.
Updated "glf" alias to pretty print git log as used by the "gl" alias.