...and make lots of changes

* source-mapping/source-map.el: New file, replacing source-object.el.
(source-map-expression, source-map-list, source-map-symbol)
(source-map-vector, source-map-string, source-map-number)
(source-map-record, source-map-hash-table, source-map-char-table)
(source-map-byte-code, source-map-other): Renamed from `source-object'.
Added "code" slot that contains a string of the original form that was
read. Documented slots.
(source-map-top-level-form): New struct. Represents a top-level form and
contains a `source-object' for that expression.
(source-map-read): Skip whitespace and comments before reading. Bind a
few edebug variables to avoid corrupting offset data.
(source-map-file): New function. Outputs a separate file containing
`source-map-top-level-form's for the supplied Elisp file.