Revert "Revert "Merge pull request #3718 from MP2E/lens_4_4_update""

This reverts commit fec81c392f255fed231d13e9ca363632648a05c5.
Update The Buttefly Effect game
Check whether Nixpkgs evaluates with NIXPKGS_ALLOW_BROKEN=1
robomongo: update to 0.8.4 and fix broken build
vym: new package

VYM (View Your Mind) is a mind-mapping program.

[Bjørn: two whitespace adjustments and quote the "$out" variable.]
libuv: Add version 0.11.29.
python-pyuv: new package

Pyuv is a Python interface to libuv, a cross-platform asychronous I/O
library.

The setup.py is tweaked to that the system version of libuv is used,
instead of tying to fetch one with git.

[Bjørn: change commit message]
haskellPackages.digestiveFunctorsAeson: Update to 1.1.11