Serials for multi-discs

[RobLoach]

@pkos

Romeo: so mostly you'll see disc 1 etc.. with the same serials
[10:45 PM] Romeo: we need to suffix those multi disc entries with "-0", "1", "2" etc
[10:46 PM] Romeo: that way on the scanner side and the backend side things match
[10:47 PM] Romeo: its not a global replace
[10:47 PM] Romeo: its per system
[10:47 PM] Romeo: some systems already have been handled by redump.org
[10:49 PM] Romeo: for example Gamecube:

[10:49 PM] Romeo:     <game name="Resident Evil 4 (USA) (Disc 1)">
        <category>Games</category>
        <serial>DL-DOL-G4BE-0-USA</serial>
        <description>Resident Evil 4 (USA) (Disc 1)</description>
        <rom name="Resident Evil 4 (USA) (Disc 1).iso" size="1459978240" crc="f5c51b40" md5="ca749757e3b9d119f3feb1f9f0f81bd7" sha1="9de89c7f6d8ffb2e27423900a39d4aec1439f4e3"/>
    </game>
    <game name="Resident Evil 4 (USA) (Disc 2)">
        <category>Games</category>
        <serial>DL-DOL-G4BE-1-USA</serial>
        <description>Resident Evil 4 (USA) (Disc 2)</description>
        <rom name="Resident Evil 4 (USA) (Disc 2).iso" size="1459978240" crc="6c83a5ff" md5="2381acd2199d6e7566932df86901903d" sha1="c75f7936814636ffe03277f363fc3427c98602ee"/>
    </game>

[10:49 PM] Romeo: see how they inserted -0- and -1- as disc labels?
[10:50 PM] Romeo: not all redump dats follow this rule