GitLab

- single-line prompt
- removed the extra line after each command output

Cleans up minimal theme by not using a custom prompt function
Removed case of 2 spaces showing if not in a version controlled folder
Adds support for svn_prompt_info

For non-trailing path components, we show only the first character. So, as in Fish proper, we convert ~/some/really/really/really/long/path/name to ~/s/r/r/r/l/p/name.