Irminsule -> Irmin

Updated refs to the appropriate name. I left the old weekly call
notes as 'Irminsule' as I do note the change of name explicitly
in one set of minutes.
Merge pull request #176 from amirmc/irmin

Irminsule -> Irmin
Merge pull request #175 from amirmc/blog

Add post on OCaml-TLS API, attacks and mitigations
tweak final post title to avoid OCaml-TLS repetition
Merge pull request #177 from avsm/master

tweak final post title to avoid OCaml-TLS repetition
acknowledge people and teams
uppercase
fix link
add daniel
count sessions, not requests
Merge pull request #178 from hannesm/thanks

acknowledge people and teams
mention horizon as well, fix links
Merge pull request #179 from hannesm/thanks

Thanks
Draft ctypes blog post.
Incorporate @avsm's suggestions for Mirage framing.
State an aspiration about the ease of switching to cross-process bindings.
Link C function symbols to their definitions (suggestion by @dbuenzli).
Ascription for the `parser_struct` definition.
Be more careful with language when describing functor instantiation.
Link to full source for expat example.