Add Mirage 1.1.0 release

This consists of a series of fairly interlocked packages, so all the
constraints have been updated in one pull request.  With this release, all OPAM
package conflicts have been removed, so it's far easier to explicitly choose at
link time which packages should be linked.

* The `mirage-types` library now fetches the types directly from the
  `mirage/mirage` repository to reduce the number of separate git repositories we
  have to track.

* Several major libraries have also been functorized to eliminate the need to
  compile them separately with Unix and Xen.  Specifically,
  `mirage-tcpip-{unix/xen}` is now deprecated in favor of `tcpip`, as is
  `mirage-http-{unix/xen}` in favor of `mirage-http`.

* The block libraries have been refreshed to use `V1_LWT` interface, and are more
  efficient at random I/O (for VHD) and use larger request sizes (for the Xen
  block driver)

* The `xenctrl` package has been replaced with `xen-evtchn` and `xen-gnt`
  to continue the support for parallel package installation without conflicts.
Merge pull request #1656 from dsheets/master

+ipaddr.2.3.0
vhd-tool: depend on OCaml 4.00.0+
xen-gnt: depend on OCaml 4.00.0+
version 0.2 for lacc
Merge pull request #1657 from UnixJunkie/newer_lacc

version 0.2 for lacc
update checksums for mirage-1.1.0 bugfix
Add cmdliner 0.9.4.
fix mirage-http dependency to require the functorized tcpip
Merge pull request #1658 from dbuenzli/master

Add cmdliner 0.9.4.
Merge branch 'master' into mirage-1.1-release
Rerelease cohttp.0.9.16

The previous version merged into OPAM was actually 0.9.15, due to
an error in creating the release tag.  This was leading to all sorts
of confusing errors in OPAM!
Merge branch 'master' into mirage-1.1-release
Merge pull request #1660 from mirage/master

Rerelease cohttp.0.9.16
Add ocaml-git 1.0.0
Merge pull request #1661 from samoht/git-1.0.0

Add ocaml-git 1.0.0
update mirage 1.1.0 urls for slipped tag (re-release)
+ ocurl 0.6.1
utop 1.11
Merge pull request #1664 from diml/master

utop 1.11