Whitespace and comment normalization in **/*.lisp

* **/*.lisp: tabs -> spaces; adapted comments to common style;
  improved one-line summaries
Changed ignored let+ bindings to &ign in src/location.lisp

* src/location.lisp (location-attribute :around location string ): in
  `let+' bindings, changed ignored bindings nil -> &ign
* xml.location.asd (system xml.location): added version "0.2" to
  system dependency on let-plus
Simplification in src/location.lisp

* src/location.lisp (maybe-decode-qname location string): simplified
Read version from xml.location.asd in xml.location-and-lisplab.asd

* xml.location-and-lisplab.asd (toplevel): load xml.location.asd
  (system xml.location-and-lisplab): use version obtained by reading
  xml.location.asd