Make geometry_list argument for curvilinear_make_uniform() optional

[veenstrajelmer]

Is your feature request related to a problem? Please describe.
curvilinear_make_uniform() contains a non-optional geometry_list argument. This geometry_list can be empty, but in this case it makes more sense to supply no geometry_list argument. This is more user friendly.

Describe the solution you'd like
Make the geometry_list argument optional

Describe alternatives you've considered
Supplying an empty list works, but is cumbersome

Additional context
MWE:

import meshkernel
import xarray as xr
import matplotlib.pyplot as plt
plt.close('all')
import numpy as np
import contextily as ctx


#general settings
lon_min,lon_max = -6,2
lat_min,lat_max = 48.5,51.2
lon_res,lat_res = 0.2,0.2
num_x = int(np.ceil((lon_max-lon_min)/lon_res))
num_y = int(np.ceil((lat_max-lat_min)/lat_res))

figsize = (10,4)
crs = 'EPSG:4326'


"""
Make a regular (potentially rotated) rectilinear grid. First generate a curvilinear grid than convert the curvilinear grid into unstructured grid. The steps are the following:
- curvilinear_make_uniform, see the following notebook: https://github.com/Deltares/MeshKernelPy/blob/AddCurvilinearGridSupport/docs/examples/04_curvilineargrid_basics.ipynb
- curvilinear_convert_to_mesh2d: https://github.com/Deltares/MeshKernelPy/blob/118cb4953c4e95d5b18ed283bb37f391134b2bb2/meshkernel/meshkernel.py#L1399 

"""

# Create an instance of MakeGridParameters and set the values
make_grid_parameters = meshkernel.MakeGridParameters() #TODO: contains default values that are maybe not intuitive
make_grid_parameters.num_columns = num_x
make_grid_parameters.num_rows = num_y
make_grid_parameters.angle = 0.0 #TODO: does non-zero result in an orthogonal spherical grid?
#make_grid_parameters.block_size = 0.0
make_grid_parameters.origin_x = lon_min
make_grid_parameters.origin_y = lat_min
make_grid_parameters.block_size_x = lon_res
make_grid_parameters.block_size_y = lat_res

grid_in_pol = False
# A polygon must to be provided. If empty it will not be used. If a polygon is provided it will be used in the generation of the curvilinear grid. The polygon must be closed
if grid_in_pol: #can be used instead of origin_x/origin_y and num_x/num_y
    pol_x = np.array([-6,-4,0,-6], dtype=np.double)
    pol_y = np.array([48,51,49.5,48], dtype=np.double)
else:
    pol_x = np.empty(0, dtype=np.double)
    pol_y = np.empty(0, dtype=np.double)
geometry_list = meshkernel.GeometryList(pol_x, pol_y)

mk1 = meshkernel.MeshKernel()
mk1.curvilinear_make_uniform(make_grid_parameters, geometry_list)

[veenstrajelmer]

In another example I saw different usage of meshkernel to get to the same result but without requiring geometry_list:

mesh2d_input = Mesh2dFactory.create(rows=noy, columns=nox, origin_x=lon_min, origin_y=lat_min, spacing_x=dx, spacing_y=dy)

mk = MeshKernel()
mk.mesh2d_set(mesh2d_input)

What is the recommended usage?

[lucacarniato]

Solved in the following pull request:

#38