strftime is ambigious

[christoph-morrison]

strftime should better written POSIX::strftime

strftime('%H:%M', localtime $storedData{$_}{'start'}),
strftime('%F_%T', localtime $data{$_}{'start'}),
strftime('%H:%M', localtime $storedData{$_}{'start'}),
::readingsBulkUpdate( $hash, 'rainDataStart', strftime '%R', localtime $dataStart);
::readingsBulkUpdate( $hash, 'rainDataEnd', strftime '%R', localtime $dataEnd );
::readingsBulkUpdate( $hash, 'rainBegin', (($rainStart) ? strftime '%R', localtime $rainStart : 'unknown'));
::readingsBulkUpdate( $hash, 'rainEnd', (($rainEnd) ? strftime '%R', localtime $rainEnd : 'unknown'));