Merge branch 'ib/scripted-parse-opt-better-hint-string' into maint

The "rev-parse --parseopt" mode parsed the option specification and the argument hint in a strange way to allow '=' and other special characters in the option name while forbidding them from the argument hint. This made it impossible to define an option like "--pair <key>=<value>" with "pair=key=value" specification, which instead would have defined a "--pair=key <value>" option. * ib/scripted-parse-opt-better-hint-string: rev-parse --parseopt: allow [*=?!] in argument hints