need to support rar 5.0 archive format

[teaspring]

rar 5.0 archive format defines new signature:
RAR 5.0 signature consists of 8 bytes: 0x52 0x61 0x72 0x21 0x1A 0x07 0x01 0x00. You need to search for this signature in supposed archive from beginning and up to maximum SFX module size. Just for comparison this is RAR 4.x 7 byte length signature: 0x52 0x61 0x72 0x21 0x1A 0x07 0x00.

but junrar has not supported the v5.0 signature yet
Please update junrar src code /com/github.com/junrar/rarfile/MarkHeader.java: isSignature() to support it