(main): Rev. 1.43 broke option -D. Its meaning in presence of -e is

(main): Rev. 1.43 broke option -D.  Its meaning in presence of -e is
unclear.  Other programs only support -e.  Remove -D.
(install_service): Remove argument datadir_set.

(main): New option -v.

(main): Exit successfully after -h.

(main): Don't print usage on unknown options, just point to -h.

(print_usage): Rewrite.  Deprecate use of non-option arguments.