Add "auto remove trailing whitespace" function

[chusiang]

Thanks @aeglos for share this magic.

" Remove trailing whitespace when writing a buffer, but not for diff files.
" From: Vigil <vim5632@rainslide.net>
function RemoveTrailingWhitespace()
    if &ft != "diff"
       let b:curcol = col(".")
        let b:curline = line(".")
        silent! %s/\s\+$//
        silent! %s/\(\s*\n\)\+\%$//
        call cursor(b:curline, b:curcol)
    endif
endfunction

"autocmd BufWritePre * call RemoveTrailingWhitespace()
map <localleader>r : call RemoveTrailingWhitespace()<cr>


" show trailing white spaces
highlight WhitespaceEOL ctermbg=red guibg=red
match WhitespaceEOL /\s\+$/