Add some commands to fix whitespace issues.

whitespace_fix.vim

" Make all tabs 4 spaces
" Make tabs delete properly
" Make autoindent add 4 spaces per indent level
set tabstop=4
set softtabstop=4
set shiftwidth=4
set expandtab " Convert all tabs
set smarttab

function! Preserve(command)
    " Preparation: save last search, and cursor position.
    let _s=@/
    let l = line(".")
    let c = col(".")
    " Do the business:
    execute a:command
    " Clean up: restore previous search history, and cursor position
    let @/=_s
    call cursor(l, c)
endfunction

nmap <leader>$ :call Preserve("%s/\\s\\+$//e")<CR>
nmap <leader>= :call Preserve("normal gg=G")<CR>