Restoring previous removed code

Fix SEGV with Python 3.

Set the main lib name according to PEP 3149

Change license to be BSD-2-Clause

submodules: use https address

sync submodule, fix python interpreter & libs versions handling, fix #50

core: fix checking of dimensions

Handle conversion from Eigen::Matrix to numpy.array or numpy.matrix

Fix wrong message error

This follows issue #44.

[CMake] Synchronize module

Add note for compiling eigenpy with python3 on macOS