Fix standalone grabbers (#1384)

* Fix too much copy/paste
* Fix typo
* Commandlineoptions: Additional error details for Int and Double ranges
* Standalone grabbers: Show fps range on error, fix default host address

libsrc/commandline/DoubleOption.cpp

@@ -19,3 +19,15 @@ double *DoubleOption::getDoublePtr(Parser &parser, bool *ok)
 
 	return nullptr;
 }
+
+bool DoubleOption::validate(Parser & parser, QString & value)
+{
+	if (ValidatorOption::validate(parser,value))
+	{
+		return true;
+	}
+
+	_error = QString("Value must be between %1 and %2.").arg(_minimum).arg(_maximum);
+
+	return false;
+}