Add 1.6 changelog to rst doc.

doc/sphinx/source/releases.rst

@@ -5,3 +5,4 @@ Release notes
    :maxdepth: 2
 
    releases/next
+   releases/v1.6.0

doc/sphinx/source/releases/next.rst

@@ -1,2 +1,11 @@
 Changes in the next release of UFL
 ==================================
+
+- Deprecate `.cell()`, `.domain()`, `.element()` in favour of
+        `.ufl_cell()`, `.ufl_domain()`, `.ufl_element()`, in multiple
+        classes, to allow closer integration with DOLFIN.
+
+- Remove deprecated properties `cell.{d,x,n,volume,circumradius,facet_area}`.
+- Remove ancient `form2ufl` script
+- Large reworking of symbolic geometry pipeline
+- Implement symbolic Piola mappings

doc/sphinx/source/releases/v1.6.0.rst

@@ -0,0 +1,30 @@
+Changes in UFL 1.6.0
+====================
+
+UFL 1.6.0 was released on 2015-07-28
+
+- Change approach to attaching `__hash__` implementation to accomodate
+  Python 3
+- Implement new non-recursive traversal based hash computation
+- Allow `derivative(M, ListTensor(<scalars>), ...)` just like list/tuple
+  works
+- Add traits `is_in_reference_frame`, `is_restriction`, `is_evaluation`,
+  `is_differential`
+- Add missing linear operators to `ArgumentDependencyExtractor`
+- Add `_ufl_is_literal_` type trait
+- Add `_ufl_is_terminal_modifier_ type` trait and
+  `Expr._ufl_terminal_modifiers_` list
+- Add new types `ReferenceDiv` and `ReferenceCurl`
+- Outer product element support in degree estimation
+- Add `TraceElement`, `InteriorElement`, `FacetElement`, `BrokenElement`
+- Add `OuterProductCell` to valid `Real` elements
+- Add `_cache` member to form for use by external frameworks
+- Add Sobolev space `HEin`
+- Add measures `dI`, `dO`, `dC` for interface, overlap, cutcell
+- Remove `Measure` constants
+- Remove `cell2D` and `cell3D`
+- Implement `reference_value` in `apply_restrictions`
+- Rename point integral to vertex integral and kept `*dP` syntax
+- Replace lambda functions in `ufl_type` with named functions for
+   nicer stack traces
+- Minor bugfixes, removal of unused code and cleanups