add strict attribute for gcmd.Command for strict option parsing

os/gcmd/gcmd_command.go

@@ -26,6 +26,7 @@ type Command struct {
 	HelpFunc      Function      // Custom help function
 	Examples      string        // Usage examples.
 	Additional    string        // Additional info about this command, which will be appended to the end of help info.
+	Strict        bool          // Strict parsing options, which means it returns error if invalid option given.
 	parent        *Command      // Parent command for internal usage.
 	commands      []Command     // Sub commands of this command.
 }

os/gcmd/gcmd_command_run.go

@@ -97,7 +97,7 @@ func (c *Command) reParse(ctx context.Context, parser *Parser) (*Parser, error)
 		}
 		supportedOptions[optionKey] = !option.Orphan
 	}
-	return Parse(supportedOptions)
+	return Parse(supportedOptions, c.Strict)
 }
 
 // searchCommand recursively searches the command according given arguments.