" Autocomplete already-existing words in the file with tab (extremely useful!)
function InsertTabWrapper()
      let col = col('.') - 1
      if !col || getline('.')[col - 1] !~ '\k'
          return "\<tab>"
      else
          return "\<c-p>"
      endif
endfunction
inoremap <tab> <c-r>=InsertTabWrapper()<cr>