Release 2.4.0 (#806)

* Update the changelog for v2.4.0

* Bump version to v2.4.0

* Drop v2.5 reference in changelog, change tpb -> ntpb

docs/source/changes.rst

@@ -1,17 +1,48 @@
 Changelog
 =========
 
-v2.4 (Development)
-------------------
-
-- Operator estimation data structures introduced in v2.2 have changed. ExperimentSetting's had
-  two members: in_operator and out_operator. out_operator is unchanged. in_operator has been
-  renamed to in_state and its data type is now ``TensorProductState`` instead of ``PauliTerm``.
-  It was always an abuse of notation to interpret pauli operators as defining initial states.
-  Analogous to the Pauli helper functions sI, sX, sY, and sZ, TensorProductStates are constructed
+v2.4 (February 14, 2019)
+------------------------
+
+Announcements:
+
+- The Quil Compiler ([``quilc``](https://github.com/rigetti/quilc)) and
+  the Quantum Virtual Machine ([``qvm``](https://github.com/rigetti/quilc)),
+  which are part of the Forest SDK, have been open sourced! In addition to
+  downloading the binaries, you can now build these applications locally from source,
+  or run them via the Docker images [``rigetti/quilc``](https://hub.docker.com/r/rigetti/quilc)
+  and [``rigetti/qvm``](https://hub.docker.com/r/rigetti/qvm). These Docker images are now
+  used as the ``services`` in the GitLab CI build plan YAML (gh-792, gh-794, gh-795).
+
+Improvements and Changes:
+
+- The ``WavefunctionSimulator`` now supports the use of parametric Quil programs, via the
+  ``memory_map`` parameter for its various methods (gh-787).
+
+- Operator estimation data structures introduced in **v2.2** have changed. Previously,
+  ``ExperimentSettings`` had two members: ``in_operator`` and ``out_operator``. The
+  ``out_operator`` is unchanged, but ``in_operator`` has been renamed to ``in_state``
+  and its data type is now ``TensorProductState`` instead of ``PauliTerm``. It was always
+  an abuse of notation to interpret pauli operators as defining initial states. Analogous to
+  the Pauli helper functions sI, sX, sY, and sZ, ``TensorProductState`` objects are constructed
   by multiplying together terms generated by the helper functions plusX, minusX, plusY, minusY,
   plusZ, and minusZ. This functionality enables process tomography and process DFE (gh-770).
 
+- Operator estimation now offers a "greedy" method for grouping tomography-like
+  experiments that share a natural tensor product basis (ntpb), as an alternative
+  to the clique cover version (gh-754).
+
+- The ``quilc`` endpoint for rewriting Quil parameter arithmetic has been changed from
+  ``resolve_gate_parameter_arithmetic`` to ``rewrite_arithmetic`` (gh-802).
+
+- The difference between ProtoQuil and QPU-supported Quil is now better defined (gh-798).
+
+Bugfixes:
+
+- Resolved an issue with post-gate noise in the pyQVM (gh-801).
+
+- A ``TypeError`` with a useful error message is now raised when a ``Program`` object is
+  run on a QPU-backed ``QuantumComputer``, rather than a confusing ``AttributeError`` (gh-799).
 
 v2.3 (January 28, 2019)
 -----------------------

pyquil/__init__.py

@@ -1,4 +1,4 @@
-__version__ = "2.4.0.dev0"
+__version__ = "2.4.0"
 
 from pyquil.quil import Program
 from pyquil.api import list_quantum_computers, get_qc