Topic/piecewise generic

Fix optional dependency to pinocchio for python bindings

[Python][Tests] remove all unecessary reshape(-1,1) in python

[Python] correctly define eigenpy matrix type for point3 and point6

Solve #19

solve #29

[CMakeList] replace hardcoded name for installation path with $PROJECT_NAME

fix hardcoded path, fix https://gepgitlab.laas.fr/loco-3d/curves/issues/22

[CMakeList] fix install path of optimization files

[Tests][Python] use Quaternion.isApprox to test equality instead of ==

Fix all compiler warnings

compute_derivate return raw pointer instead of shared_ptr (to use covariant return type, required for python API)