(jka-compr-compression-info-list)

(jka-compr-compression-info-list)
(jka-compr-mode-alist-additions, jka-compr-load-suffixes):
Give :set functions to provide automatic updating.
Update docstring.  Give compiler defvars early in the file
and move the defcustoms to a later spot where all called functions
are defined.
(jka-compr-file-name-handler-entry): Doc fix.
(jka-compr-compression-info-list--internal)
(jka-compr-mode-alist-additions--internal)
(jka-compr-load-suffixes--internal): New variables.
(jka-compr-install): Set the three above variables.
Update `load-file-rep-suffixes' instead of `load-suffixes'.
(jka-compr-update, jka-compr-set): New functions.
(auto-compression-mode): Doc fix.

These changes are installed in two steps to provide better diffs.
The present revision makes no sense without the next one.