Enable require_order of Getopt::Long.

From this change, shly reads command-line options from the first and terminates parsing when a non-option argument appears.
Refactored.
Make terminate allow to take a format-string.
Allow -I to specify directories for asdf:*central-registry*. -I has been used a shorthand for --impl, though.
Allow multiple -L options.
Add a command load-dump-core. (Experimental)
ver 0.6.0