Use plists to record handlers.

Use plists to record handlers.
(jka-compr-insert-file-contents): Don't leave buffer locked.
Call the standard function, and file-local-copy,
using jka-compr-run-real-handler.
(jka-compr-file-local-copy): Call file-local-copy
using jka-compr-run-real-handler.
(jka-compr-write-region): Likewise.
(jka-compr-load): Don't alter file-name-handler-alist.
Do bind inhibit-file-name-handlers and inhibit-file-name-operation.
(jka-compr-handler): Don't alter file-name-handler-alist.