This adds some additional options to the ones set in Debian's /etc/vimrc.

" enable syntax highlighting
syntax on

" Highlight redundant whitespaces and tabs.
highlight RedundantSpaces ctermbg=red guibg=red
match RedundantSpaces /\s\+$\| \+\ze\t\|\t/

" use 4 spaces instead of tabs
set tabstop=4
set shiftwidth=4
set expandtab
set softtabstop=4

" always show ^M in DOS files
set fileformats=unix

" my terminal is white on black
set background=dark
highlight Comment ctermbg=blue
highlight Comment ctermfg=white

" always show line and col number and the current command, set title
set ruler
set showcmd
set title titlestring=vim\ %f

" caseinsensitive incremental search
set ignorecase
set incsearch

" Show matching brackets
set showmatch

" disable any autoindenting which could mess with your mouse pastes (and your head)
" (not useing 'set paste' here to keep fancy stuff like tab completion working)
set nocindent
set nosmartindent
set noautoindent
set indentexpr=
filetype indent off
filetype plugin indent off

" enable php auto folding and remap folding keys to + - (and shift variants)
let php_folding=1
map + zo
map * zR
map - zc
map _ zM

" This function determines, wether we are on the start of the line text (then tab indents) or
" if we want to try autocompletion
func! InsertTabWrapper()
    let col = col('.') - 1
    if !col || getline('.')[col - 1] !~ '\k'
        return "\<tab>"
    else
        return "\<c-p>"
    endif
endfunction

" Remap the tab key to select action with InsertTabWrapper
inoremap <tab> <c-r>=InsertTabWrapper()<cr>
filetype on           " Enable filetype detection
filetype plugin on

" function to cleanup a text -> mapped to F5
fun CleanText()
    let curcol = col(".")
    let curline = line(".")
    exe ":retab"
    exe ":%s/^M$//ge"
    exe ":%s/^M/ /ge"
    exe ":%s/ \\+$//e"
    call cursor(curline, curcol)
endfun
map <F5> :call CleanText()<CR>

Be sure you make the ^M using “CTRL-V CTRL-M” NOT BY TYPING “CARROT M”!