Mulensmodel

* new import of C and C++ code using extensions - should work in basically any python

Also example 16 was added - it's a high-level code for fitting microlensing models.

* Model.plot_lc() got new kwargs: gamma and bandpass

* UniformCausticSampling class added (implements Cassan 2008 method), hence, new model parameters were added: x_caustic_in, x_caustic_out, t_caustic_in, and t_caustic_out

* DATA_PATH added - replaces MODULE_PATH in many places
* whole data/ directory included in setup.py

* fit_blending option added in Model.plot_lc()

* Coordinates.v_Earth_projected() added
* Event.get_ref_fluxes() - fit_blending option added
* Model.get_ref_fluxes() - fit_blending option added
* Utils.velocity_of_Earth() added