Fix Common Git Mistakes by Chris Achard

• Change a Commit Message that Hasn't Been Pushed Yet
• Add More Files and Changes to a Commit Before Pushing
• Remove Files from Staging Before Committing
• Remove Changes from a Commit Before Pushing
• Use and Compare the Different git Reset Options: --hard, --soft, and --mixed
• Recover Local Changes from `git reset --hard` with `git reflog`
• Undo a Commit that has Already Been Pushed
• Copy a Commit from One Branch to Another
• Move a Commit that was Committed on the Wrong Branch
• Use `git stash` to Save Local Changes While Pulling
• Explore Old Commits with a Detached HEAD, and then Recover
• Fix a Pull Request that has a Merge Conflict
• Cleanup and Delete Branches After a Pull Request
• Change the Commit Message of a Previous Commit with Interactive Rebase
• Add a File to a Previous Commit with Interactive Rebase
• Fix Merge Conflicts While Changing Commits During an Interactive Rebase
• Squash Commits Before they are Pushed with Interactive Rebase
• git Ignore a File that has Already been Committed and Pushed
• Completely Remove a File from Pushed git History
• Push a New Branch to github that Doesn't Exist Remotely Yet