Bump to 4.3.0 and write changelog

[skip ci]

Author: aantron

CHANGES

@@ -1,3 +1,37 @@
+===== 4.3.0 (2019-08-20) =====
+
+====== Planned to break in 5.0.0 ======
+
+  For general discussion of breakage in Lwt 5.0.0, see #584. See #293 about how
+  Lwt announces and does breaking changes.*
+
+  * The signature of Lwt.async will change from (unit -> 'a Lwt.t) -> unit to
+    (unit -> unit Lwt.t) -> unit (#603, prompted @cfcs).
+  * Lwt_unix.send_msg and Lwt_unix.recv_msg will be changed to take
+    Lwt_unix.IO_vectors.t instead of Lwt_unix.io_vectors (#702, prompted
+    Marcello Seri).
+  * Nesting calls to Lwt_main.run will be forbidden, and will raise an
+    Failure. Most programs don't do this (#609, prompted François-René Rideau).
+  * configure.ml will be removed in favor of an improved discover.ml This
+    affects only users who are configuring Lwt as part of a manual installation
+    (i.e., not users of opam or esy). See discover.ml for usage (#700).
+  * Lwt_unix.async_method will have no effect. In practice, it already does
+    nothing, and has almost no users (#572).
+
+====== Additions ======
+
+  * Lwt_process: allow setting working directory for new processes (#694, Thomas
+    Leonard).
+  * PPX: use OCaml 4.08 ASTs to support latest features (#697).
+  * Lwt_io.NumberIO: use compiler intrinsics for better performance (#178,
+    requested Mauricio Fernandez).
+
+====== Bugs fixed ======
+
+  * Race condition in Lwt_react.S.limit (4e592eb).
+  * Use fallback rule during configuration (#693, Hongchang Wu).
+  * Fix typos (#688, #692, @Fourchaux).
+
 ===== 4.2.1 (2019-04-02) =====
 
 ====== Bug fixed ======

README.md

@@ -1,6 +1,6 @@
-# Lwt    [![version 4.2.1][version]][releases] [![Gitter chat][gitter-img]][gitter] [![Travis status][travis-img]][travis] [![AppVeyor status][appveyor-img]][appveyor]
+# Lwt    [![version 4.3.0][version]][releases] [![Gitter chat][gitter-img]][gitter] [![Travis status][travis-img]][travis] [![AppVeyor status][appveyor-img]][appveyor]
 
-[version]:      https://img.shields.io/badge/version-4.2.1-blue.svg
+[version]:      https://img.shields.io/badge/version-4.3.0-blue.svg
 [releases]:     https://github.com/ocsigen/lwt/releases
 [gitter-img]:   https://img.shields.io/badge/chat-on_gitter-lightgrey.svg
 [travis]:       https://travis-ci.org/ocsigen/lwt/branches