Removing some warning when compiling ledger-mode

* ldg-commodities.el: use #' instead of ' for function quoting
 * ldg-exec.el: remove the fit-frame function that don't exists and do
   not use toggle-read-only to make the buffer read-only
 * ldg-report.el: use forward-line instead of next-line

There are still some warning because of the use of gensym in place of make-symbols.