Setting a non-existant path component to PATH logs an error to stderr.
This is not appropriate for non-interactive temporary modifications,
like the one done by the `sudo` completion helper function.
__fish_complete_subcommand
* sudo:
- now can be completed bu group and user (-u and -g keys).
- subcommand completion is fixed
* __fish_complete_proc.fish is added to complete killall command with
list of running processes
* __fish_complete_tex.fish is updated with common options
* __fish_make_completion_signals.fish is added to make a list of kill
signals for kill and killall
* completions:
- minor filetype completions are added for djview, xpdf, mupdf, gv,
xdvi
- adduser is copmleted by user and group
- dlocate and dpkg are completed by packages
- find: -executable options is added
- htop: options
- funced and funcsave are completed by function names
- ifdown and ifup are copmleted by interfaces
- kill and killall: options, signals and processes
- latexmk, ln, nm: options
- lualatex and xelatex copmletions
- sudo: -u and -g options
- wvdial: presets
