Remove support for Solver::Options::solver_log.

This is not really used and if needed can be implemented
in user code.

Change-Id: I56328d51c9d3788f90c751ff9c3a5937989f6ee0

docs/source/solving.rst

@@ -1522,17 +1522,6 @@ elimination group [LiSaad]_.
    iteration. This setting is useful when building an interactive
    application using Ceres and using an :class:`IterationCallback`.
 
-.. member:: string Solver::Options::solver_log
-
-   Default: ``empty``
-
-   If non-empty, a summary of the execution of the solver is recorded
-   to this file.  This file is used for recording and Ceres'
-   performance. Currently, only the iteration number, total time and
-   the objective function value are logged. The format of this file is
-   expected to change over time as the performance evaluation
-   framework is fleshed out.
-
 :class:`ParameterBlockOrdering`
 -------------------------------
 

docs/source/version_history.rst

@@ -4,6 +4,16 @@
 Releases
 ========
 
+HEAD
+====
+
+Backward Incompatible API Changes
+---------------------------------
+
+#. ``Solver::Options::solver_log`` has been removed. If needed this
+   iteration callback can easily be implemented in user code.
+
+
 1.9.0
 =====