package removal proposal: www/aipo

[Takahiro Kambe <taca%NetBSD.org@localhost>]

Hi,

Open source version of Aipo (www/aipo) was provied by TOWN,Inc.
And TOWN,Inc. ended this open source version on 31th March 2018 and no
distfile is available from the official site.

So, it's time to remove from pkgsrc.  If anyone knows some active fork
exists, please tell me.  I'll remove the pacakge before next pkgsrc branch.

Best regards.

-- 
Takahiro Kambe <taca%NetBSD.org@localhost>