3.5.0

CHANGES:

New features:

• Add Codecs.serialize_{fold,iter}_copyless (@Cjen1, #71).
  Avoids a copy when writing out fragments.

Documentation:

• Add example of how to use the library (@rottened23, #62).

• Extract LICENSE and identify as BSD-2-Clause (@tmcgilchrist, #80).

Build system:

• Remove compiler flags for flambda (@talex5, #83).
  This was very slow to compile on OCaml 4.14, and the performance benefit is minimal.

• Update to dune 2 (@talex5, #77).

• Dune should not be a build dependency (@talex5, #67).

• Replace Uint32.of_int in unit-tests with of_string (@talex5, #73).
  Fixed tests on 32-bit systems.

• Remove Travis CI (@talex5, #74). Replaced by ocaml-ci.

• Switch from "capnpc" to "capnp compile" (@talex5, #75).

• Benchmarks: remove incorrect test for 64-bit on Windows (@dra27, #72).