refactor(bash): use PS1 for prompt customization instead of PROMPT_COMMAND
refactor(bash): use PS1 for prompt customization instead of PROMPT_COMMAND

This patch updates bash prompt customization so that it uses PS1
embedding commands instead of PROMPT_COMMAND. Still WIP, there's a bug
in character count in history and the prompt symbol doesn't change color
on previous exit command value.

ref: https://wiki.archlinux.org/index.php/Bash/Prompt_customization#Embedding_commands

anchnk/dotfiles,anchnk/dotfiles,anchnk/dotfiles