3rd option for file handling

src/App/Gui.hs

@@ -60,6 +60,9 @@ runEditor f = do
          -> ByteString.Lazy for lazy, fast
      - Text.IO.hGetContents: strict, needs 2x file size while reading in
          -> filesize == 2xRAM = bad
+     - Pass the handler around instead of filename, close at exit
+         -> works with all above options (incl. the lazy variants, i think)
+         -> locks the file MultiReader/SingleWriter for free (i think)
   -}
   content `seq` hClose handle
   BrickMain.defaultMain theApp (initialState f content)