GitLab

Actually replace the value of the environment variable $HOME with
"~" instead of appending the tilde in front of the prompt.

When the current path is /home/user/.config/doublecmd the prompt
now reads "/h/u/.c/doublecmd", not "/h/u/./doublecmd" as was the
case. This matches what the Fish shell does.

Enclose the Perl snippet in single quotes instead of double quotes.

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.

The git status indicators were taken from sorin.zsh-theme and changed to
use ASCII symbols instead of Unicode ones because my preferred terminal
font, DejaVu Sans Mono, renders Unicode symbols poorly and also because
Unicode rendering is not available in standard Linux virtual terminals.