Merge pull request #2307 from yallop/ctypes-0.3.1

Add ctypes 0.3.1
Moved GPR to GitHub
Moved gsl-ocaml to GitHub
bibtex2html version 1.98
Merge pull request #2314 from backtracking/master

bibtex2html version 1.98
mirage-entropy-xen-0.1.4
mirage-entropy-unix-0.1.4
from mirage/build: WITH_LWT=ocamlfind query lwt cstruct ipaddr <- adding ipaddr as dependency
add ipaddr here as well
Add ctypes 0.3.2 release.
+cmdliner.0.9.5
Merge pull request #2317 from dbuenzli/cmdliner-0.9.5

+cmdliner.0.9.5
Merge pull request #2316 from yallop/ctypes-0.3.2

Add ctypes 0.3.2
Merge pull request #2312 from mmottl/master

Moved GPR to GitHub
sha.1.9: build on FreeBSD from vincenthz/ocaml-sha#12
Merge pull request #2320 from dsheets/master

sha.1.9: build on FreeBSD from vincenthz/ocaml-sha#12
+uri.1.7.1
Merge pull request #2311 from djs55/vhd

vhd-format.0.7.1 and vhd-tool.0.7.5
Merge pull request #2321 from avsm/master

+uri.1.7.1
+cstruct.1.3.0