* command.h: Update copyright.

* command.h: Update copyright.
(struct cmd_list_element): Replace definition with opaque
declaration.
(enum cmd_types): Document that it will eventually be moved to
cli/cli-decode.h
(CMD_DEPRECATED, DEPRECATED_WARN_USER): Delete macros.
(MALLOCED_REPLACEMENT): Delete macro.
* Makefile.in (cli_decode_h): Add $(command_h).
(top.o, completer.o, maint.o): Add dependency on $(cli_decode_h).
* top.c: Include "cli/cli-decode.h".
* completer.c: Include "cli/cli-decode.h".
* maint.c: Include "cli/cli-decode.h".
* cli/cli-decode.h: Include "command.h".
(enum command_class): Delete.
(enum cmd_types): Comment out.
(enum cmd_auto_boolean): Delete.
(enum var_types): Delete.