More options for color in pdksh

pdksh uses an arbitrary, non-printing character to delimit color escape sequences, but no one character works well in all operating systems and on all terminals. This update

• Uses \021 instead of \016 for better support of NetBSD and OpenBSD (props @scuzzilla)
• Allows the user to specify their own non-printing character by setting the environment variable POLYGLOT_NP
• Allow the user to turn of color for pdksh by setting POLYGLOT_PDKSH_COLORS=0

Support for oksh and osh; prevent login loop

• The Polyglot Prompt now supports the oksh and osh shells.
• A potential login loop is now avoided (#16).

Support for yash

• The yash shell is now supported (props to @awkless).
• I have removed inverse video display for superuser mode in a few instances where it does not work reliably.

Fixed vi command mode display on Zsh

Props to @edklem for identifying the bug and proposing the fix.

New non-printing character for color escape sequences in pdksh

pdksh requires non-printing characters as delimiters for color escape sequences. In the past, the Polyglot Prompt has used \021, but that is visible in Windows Terminal, so I have switched to \016.

Bug fix: dash as login shell

dash is now recognized correctly when it is the login shell. Props to @ansimita.

virtualenv/venv/pipenv/poetry/conda Support

The Polyglot Prompt will now display virtual environments created using virtualenv, venv, pipenv, poetry, and conda.

POLYGLOT_SHOW_UNTRACKED; bug fixes

• Git status calculation for untracked files may now be turned off by setting POLYGLOT_SHOW_UNTRACKED=0. Doing so has the effect of speeding up the prompt display considerably when one is working with extraordinarily large repositories.
• dash is now correctly recognized when it is a login shell.
• The @ sign was not displaying between the username and the hostname in ZSH. This has been corrected.

Various improvements

• Eliminated subshell by combining the _polyglot_branch_status and _polyglot_branch_changes functions
• Exit gracefully if there is no command command (which is occasionally the case with busybox ash)
• zsh
  • Eliminated subshell when zsh calculates hostname string
  • Do not output warnings if WARN_CREATE_GLOBAL or WARN_NESTED_VAR has been set
  • The vi-mode indicator will not work with a dumb terminal, so it is disabled when $TERM == dumb

dash invoked as sh; UWIN support

• The Polyglot Prompt now loads in dash when it is invoked from a sh symlink
• Support for UWIN