chicken: 4.11.0 -> 4.13.0

Also update the chicken-ssql egg dependency version for ugarit and
ugarit-manifest-maker from 0.2.2 to 0.2.4 to include a fix for an issue
uncovered by chicken-4.13.0 (see [1] and [2] for more info).

[1]: https://bitbucket.org/DerGuteMoritz/ssql/pull-requests/1
[2]: https://salmonella-linux-x86-64.call-cc.org/chicken-4/gcc/linux/x86-64/2017/04/19/yesterday-diff/log2/install/ssql.html