newline segment not useful anywhere else than at the end

[thmxv]

The current newline segment does 2 things, it adds a newline but it also adds the $/# 'prompt character'; which renders it useless for use at the start or in the middle of a prompt. To work around those issue I had to create 2 custom segments of my own, one for just a newline and one for just the prompt character. However those rely on un-documented private implementation details of trueline and I would prefer if they were included upstream. I think replacing the current newline segment by those 2 new segments would give more flexibility for all users.

_trueline_my_newline_segment() {
    local fg_color="$1"
    local bg_color="$2"
    local font_style="$3"
    local segment="$(_trueline_separator default_bg)"
    segment+="\n"
    PS1+="$segment"
    unset _last_color
}

_trueline_prompt_char_segment() {
    local fg_color="$1"
    local bg_color="$2"
    local font_style="$3"
    local is_root="$(_trueline_is_root)"
    local newline_symbol="${TRUELINE_SYMBOLS[newline]}"
    if [[ -n "$is_root" ]]; then
        local newline_symbol="${TRUELINE_SYMBOLS[newline_root]}"
    fi
    local segment="$(_trueline_separator)"
    segment+="$(_trueline_content "$fg_color" "$bg_color" "$font_style" " $newline_symbol ")"
    PS1+="$segment"
    _trueline_record_colors "$fg_color" "$bg_color" "$font_style" true
}