Minor hacks and big update of TODO.rest

* Tweaks to the asdf converter and the way the first-file-form is read.
* Big update of the TODO file, including annotations of items with priorities.
* small update to the INTERNALs description and ilc09 presentation summary.
* Some utility functions to deal with pathnames somewhat portably.
* Renaming of string escaping functions, enhancement to with-output macro.