KiriKiri support

[holly-hacker]

Used by the Nekopara series (w/ E-mote), file extension is .xp3

[Azukee]

Source from the original KiriKiriZ project for reference: here

[Azukee]

Started work on this with the Kirikiri branch

[Azukee]

Added initial support for some Nekopara files in 80dcb47
Please note that other games might not work with this unpacker since they use different encryption techniques, please also note that this is not the final version of the XP3 unpacker, but it'll work for some files of Nekopara