add robotbuilder: a lib to generate robot models

and use it to generate the benchmarks

robotbuilder
------------

Enable a client program to generate the C++ source code for a metapod model.

One should:

 * call the setters configure the robotbuilder
 * call addLink repetively to describe its robot
 * call write to trigger the write.

The eventual files are generated from template texts.

In order to avoid the plain of manually embedding (and escaping) the
template text, the embedfile utility was used.

The library is not as clean as it could, but since the generated code
is changing a lot in the fusion branch, the robotbuilder cleaning is
done in this branch too.

The generated headers include a config.hh file generated from the same
template as jrl-cmake, except for the LIBRARY_VERSION macro, which has
been removed.

The resulting source code is independent from [jrl-]cmake.

embedfile
---------

Convert anu file into a C source file so that it can be included into an
application or a library.
make_model: generate only one model per call

during parallel builds, make_model was called several times concurrently
(presumably once per sample model build directory).

Since it generated all the models at once, models were generated multiple
times, concurrently. This is inefficient and might also explain "lack of
rebuild" I noticed.

This commit fixes that by adding a `depth` parameter to make_model which
tells it which model to generate.

The models where also renamed from sample_${nbdof}_dof to sample_${depth}
to simplify the CMakeLists.txt.
homogenize location of config.hh files
fix OperatorMul< Vector6d, Inertia, ConstraintMotionAnyAxis>
robotbuilder: use boost::algorithm instead of regex

because the functor variant of boost::regex_replace is not available in
boost 1.40 (it was introduced in 1.42).
embedfile: do not depend on boost>1.40 features
Includes boost/filesystem/convenience.hpp if boost version is 1.40.0
Merge branch 'topic/add_robotbuilder'