The non-linear least squares solver had the ability to update the
user's parameters every iteration. Now GradientProblemSolver can
do the same.
Also a few minor Sphinx markup related cleanup to the documentation
which were found in the process of updating Sphinx on my machine
and adding the docs for this feature.
This fixes https://github.com/ceres-solver/ceres-solver/issues/246
Change-Id: Ib6b90ac22be8bfb60b14f25ad52082ba371af164
The test makes sure the Rosenbrock function is correctly minimized from the
canonical starting point using the default settings.
Change-Id: Iea820f976707bde37162981c5db87fac5167ba9e