[python] create parent class 'curve3' for all the curves of fixed dimension 3, bezier3 correctly inherit of this class

Topic/fix bezier3 python

See merge request loco-3d/curves!27

Pfernbac/curves python inheritance

See merge request loco-3d/curves!26

Release of version 0.2.0.

Devel

See merge request loco-3d/curves!20

Topic / add functions to get waypoints of bezier and coeff of polynomial (for python)

See merge request loco-3d/curves!21

Add new methods in polynomial and piecewise polynomial

See merge request loco-3d/curves!19

Topic/add bezier3 python binding

See merge request loco-3d/curves!18