"From http://vim.wikia.com/wik - Dick Moores - f121f203b

"From http://vim.wikia.com/wiki/Disable_F1_built-in_help_key
inoremap <F1> <Esc>
noremap <F1> :call SophHelp()<cr>

function! MapF1()
  if buftype == "help"
    exec 'quit'
  else
    exec 'help'
  endif
endfunction

function! SophHelp()
  if &buftype=="help" && match( strpart( getline("."), col(".")-1,1), "\\S")<0
    bw
  else
    try
      exec "help ".expand("<cWORD>")
    catch /:E149:/
      exec "help ".expand("<cword>")
    endtry
  endif
endfunc