Problem::Evaluate implementation.

1. Add Problem::Evaluate and tests.
2. Remove Solver::Summary::initial/final_*
3. Remove Solver::Options::return_* members.
4. Various cpplint cleanups.

Change-Id: I4266de53489896f72d9c6798c5efde6748d68a47

docs/source/modeling.rst

@@ -1110,6 +1110,64 @@ Instances
    The size of the residual vector obtained by summing over the sizes
    of all of the residual blocks.
 
+.. function:: bool Problem::Evaluate(const Problem::EvaluateOptions& options, double* cost, vector<double>* residuals, vector<double>* gradient, CRSMatrix* jacobian)
+
+   Evaluate a :class:`Problem`. Any of the output pointers can be
+   `NULL`. Which residual blocks and parameter blocks are used is
+   controlled by the :class:`Problem::EvaluateOptions` struct below.
+
+   .. code-block:: c++
+
+     Problem problem;
+     double x = 1;
+     problem.Add(new MyCostFunction, NULL, &x);
+
+     double cost = 0.0;
+     problem.Evaluate(Problem::EvaluateOptions(), &cost, NULL, NULL, NULL);
+
+
+   The cost is evaluated at `x = 1`. If you wish to evaluate the
+   problem at `x = 2`, then
+
+   .. code-block:: c++
+
+      x = 2;
+      problem.Evaluate(Problem::EvaluateOptions(), &cost, NULL, NULL, NULL);
+
+   is the way to do so.
+
+   **NOTE** If no local parameterizations are used, then the size of
+   the gradient vector is the sum of the sizes of all the parameter
+   blocks. If a parameter block has a local parameterization, then
+   it contributes "LocalSize" entries to the gradient vector.
+
+.. class:: Problem::EvaluateOptions
+
+   Options struct that is used to control :func:`Problem::Evaluate`.
+
+.. member:: vector<double*> Problem::EvaluateOptions::parameter_blocks
+
+   The set of parameter blocks for which evaluation should be
+   performed. This vector determines the order in which parameter
+   blocks occur in the gradient vector and in the columns of the
+   jacobian matrix. If parameter_blocks is empty, then it is assumed
+   to be equal to a vector containing ALL the parameter
+   blocks. Generally speaking the ordering of the parameter blocks in
+   this case depends on the order in which they were added to the
+   problem and whether or not the user removed any parameter blocks.
+
+   **NOTE** This vector should contain the same pointers as the ones
+   used to add parameter blocks to the Problem. These parameter block
+   should NOT point to new memory locations. Bad things will happen if
+   you do.
+
+.. member:: vector<ResidualBlockId> Problem::EvaluateOptions::residual_blocks
+
+   The set of residual blocks for which evaluation should be
+   performed. This vector determines the order in which the residuals
+   occur, and how the rows of the jacobian are ordered. If
+   residual_blocks is empty, then it is assumed to be equal to the
+   vector containing all the parameter blocks.
 
 ``rotation.h``
 --------------