Darkcoin: new package (v0.9.13.15)

Darkcoin is a privacy-centered crypto-currency.
Litecoin: Update to 0.9.3-preview5

Now Litecoin expression lives in a single file, litecoin.nix
fix sloccount build
x86info: ignore warnings
folly: 12 -> 17, fix build
minixml: update from 2.8 to 2.9
nixos/installer: Override swap devices so tests don't fail

This patch should be reverted if either:
  - systemd fixes the multi-swapon issue.
    https://bugs.freedesktop.org/show_bug.cgi?id=86930
  - If we disable the autogeneration of swap and vfat units within
    systemd.
nixpkgs: afl 0.79b -> 0.85b

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Update libtoxcore and qtox to the newest dev version

As from now qtox depends on openalSoft instead of openal. This is due to
incompatibilities between those to two implementations. Anyway, this
should be okay because their official debian package depends on
openalSoft as well.
toxic: Update to the newest dev version

This update is necessary due to API changes in libtoxcore. Sad to say that
the recent stable version doesn't work with our libtoxcore. We need to
update to the recent dev version.
utox: Update to the newest dev version

This update is necessary due to API changes in libtoxcore.
nixUnstable: bump
nix-exec: bump
haskellPackages.hoopl: new expression 3.10.0.1
haskellPackages.unboundGenerics: new expression
Add pythonPackages.icalendar
srecord: update 1.63 -> 1.64

libgcrypt was an optional dependency in previous versions too, but in
this version the build fails unless libgcrypt is there, or
--without-gcrypt is passed to configure.

Since libgcrypt only increases the closure size from 131 MiB to 136 MiB,
I'm adding it as a dependency.

[1]: http://srecord.sourceforge.net/change_log.txt
KDE4: fix kdepim build
Add olcai to maintainers

Takes maintainership of pythonPackages.icalendar as well
Merge pull request #5218 from olcai/icalendar

Add pythonPackages.icalendar