Add continuous DPPs

Hi guys,

I am proposing an implementation of continuous DPP samplers associated to Fourier and Jacobi eigenfunctions

• Projection DPPs with Gram-Schmidt like algorithm Hough et al.
• Generic DPPs
  • Naive spectral method
  • Dominated CFTP for Fourier adapting Decreusefond et al.

TODOs:

• add relevant docstrings with references to other functionalities and bibliography
• add tests
• think of code optimization
• CFTP possible for Chebychev