test/python: set default converter for Eigen::Matrix objects

[Doc] Add a cheat sheet

Fix setting of BOOST_MPL_LIMIT_LIST_SIZE

Make silent the warning from EigenPy >= 1.6.0

Fix usage of row major matrices + fix doc.

Fix issue related to #885

Improve coverage of Spatial classes

algo/derivatives: use const references

Avoid useless memory allocation.

cmake: sync submodule

Topic/constrained dynamics

python: fix missing pin.