fix potential deadlock in lwt_unix_recv_notifications

caml_alloc_tuple may provoke a thread switch and an unfortunate
send_notification call will deadlock on notification_mutex
still being held by recv_notifications
Merge pull request #40 from ygrek/fix

fix potential deadlock in lwt_unix_recv_notifications
fix: «pick» is closer to «choice» than «join»
Merge pull request #42 from malo-denielou/master

«pick» is closer to «choice» than «join»
Lwt_log: get backtrace early to overcome exns in Printexc.to_string.
Add Lwt_sequence.find_node_* functions
Merge pull request #45 from nojb/master

Add Lwt_sequence.find_node_* functions
Support for React 1.0.0.

React.S.bind is now provided and the interface of React.S.switch
changed.
Merge pull request #47 from dbuenzli/master

Support for React 1.0.0.
fixes to README.

Note that I bumped the OCaml minimum version up to 3.12.1, as that's
mostly what we test with these days.  Also replaced GODI with OPAM
since the former is now offline.
Fix my fixes to the README, via @hcarty
Merge pull request #49 from avsm/README-fixes

fixes to README.
Fix ocaml/camlp4#19
Lwt_ssl: expand API to allow setting socket options with Ssl functions.
Document Lwt_ssl.ssl_perform_handshake and ssl_accept_handshake.
Merge pull request #50 from mfp/ssl-uninitialized-socket

Minor Lwt_ssl API addition to support Ssl functions used to set socket options before handshake
Merge pull request #51 from mfp/preserve-backtraces

Lwt_log: get backtrace early to overcome exns in Printexc.to_string.
version 2.4.5
use sys_exit when Unix.execv fail

User have reported problems related to exit hooks.
Fixes to discover.ml: calling the linker with compiler flags is bad and causes
failures under Windows.