author name once followed by contributed and changed files.
Improve selection of entries to include in list, and generate list
of unrecognized entries indicating syntax errors in ChangeLog files.
(authors-coding-system): New variable.
(authors-many-files): Update doc string.
(authors-aliases): Change format. Now one entry with multiple
aliases per author.
(authors-valid-file-names, authors-renamed-files-alist)
(authors-renamed-files-regexps): New variables.
(authors-canonical-file-name): New function. Validates that file
exists or occurs in one of the above lists. Record unrecognized
file names in global authors-invalid-file-names list.
(authors-add): Change to record per-change counts.
(authors-canonical-author-name): Handle new format of
authors-aliases list.
(authors-scan-change-log): Rename FILE arg to LOG-FILE.
Change doc string to describe new entry format.
Only add author entries for valid file names.
(authors-print): Replace by authors-add-to-author-list.
(authors-add-to-author-list): New function which reorders
per-file entries and adds them to global authors-author-list.
(authors): Instead of authors-print to insert in *Authors* buffer,
use authors-add-to-author-list to reorder the list and then
insert result in *Authors* buffer with new format.
Generate *Authors Errors* compilation-mode buffer listing
unrecognized ChangeLog entries.
