kernel: Enable PPP_FILTER by default.

pppd will try to use it to improve efficiency and complain if it's not available
(but is is not mandatory).
synaptics: fix tapButtons setting
crawl: fix, update, add console version
Add flannel, etcd backed network fabric for containers
docker: propagate nix.proxy into daemon environment
nixos/git-daemon: add types
nixos/git-daemon: add 'user' and 'group' options
nixos/git-daemon: fix 'exportAll' option
ocamlnet: update from 3.7.6 to 3.7.7
ocaml-http: update from 0.1.3 to 0.1.5
Merge pull request #4887 from vbgl/ocamlnet

Updates ocamlnet and ocaml-http
kernel: Add more supported features
rematch: add haskell package
distributed-process-platform: add haskell package
Merge pull request #4780 from ambrop72/kernel-ppp-filter

kernel: Enable PPP_FILTER by default.
fix ccnx build
Merge pull request #4870 from bosu/docker-proxy

docker: propagate nix.proxy into daemon environment
fix libreoffice build
Revert "nixos: installation: make installation ISOs USB bootable"

This reverts commit b7f6a138b13ca667464b31274a33124d252ebc8b.
Revert "nixos: iso-image: use syslinux bootloader for USB booting support"

This reverts commit 455db168b30d53c903c96be80ef843b79e0744ae.