Fix edge case in Diff.class.php causing it to error out
Fix edge case in Diff.class.php causing it to error out

Previously it was possible for the startOffset and endOffset to overlap
for certain arrays, causing the algorithm to completely fall apart.

WoltLab/WCF,cashcat/WCF-1,SoftCreatR/WCF,MenesesEvandro/WCF,Cyperghost/WCF,SoftCreatR/WCF,MeinAccount/WCF,Cyperghost/WCF,MenesesEvandro/WCF,WoltLab/WCF,Morik/WCF,0xLeon/WCF,MeinAccount/WCF,Morik/WCF,ramiusGitHub/WCF,ramiusGitHub/WCF,joshuaruesweg/WCF,SoftCreatR/WCF,WoltLab/WCF,WoltLab/WCF,Cyperghost/WCF,0xLeon/WCF,cashcat/WCF-1,NBZ4live/WCF,Cyperghost/WCF,joshuaruesweg/WCF,Morik/WCF,SoftCreatR/WCF,Morik/WCF,joshuaruesweg/WCF,Cyperghost/WCF,0xLeon/WCF,NBZ4live/WCF