Merge pull request #768 from ZyX-I/tbsh-update-trouble

Add troubleshooting questions regarding updating
Handle non-printable characters properly

Fixes #723
Use .copy() on character_translations before modifying
Make powerline work with non-utf filenames

Fixes #281
Do not do needless copying in test_shells/test.sh
Remove backslash escaping on zsh and fish
Add tests for special characters escaping