Interpolate, Differentiate, Integrate are now algorithmic struct which can be efficiently overloaded.

Fix some bugs in:
  - display of visuals
  - fix packaging for Python

Changelog:

  - solve several bugs in the API
  - migrate API of Model and Geometries to satisfy HPP requierements
  - improve global packaging: the Python bindings is now an independant project

* Do not let cmake guess the system library directory, always use "lib"
* Add a missing <cmath> header for isnan().

* Disable parallel builds as g++ processes consumes loads of memory
* Fix PLIST
* Fix DEPEND_ABIs: drop useless requirements on assimp, add minimum 3.0 version
  on urdfdom
* Drop specific user settings (PREFER.*)
* Explicitly set cmake build options
* Sort dependencies

patch-aa: ensure that cmake does not find unwanted optional dependencies
patch-ab: fix a quoting issue in a cmakefile
patch-ac: fix build with assimp-2

This new version fixes several bugs in the geometry module. It also provides a fully compatible version of the collision pairs and distance computations to obstacles.