Function for downloading zenodo calibration

[zauster]

Builds on PR #134

Usage:

at = download_zenodo_calibration_object("AT");
import BeforeIT as Bit
parameters, initial_conditions = Bit.get_params_and_initial_conditions(at, Bit.DateTime(2020, 03, 31);
    scale = 1 / 1000)
model = Bit.Model(parameters, initial_conditions)

[zauster]

@aldoglielmo @ameligrana reviewable now

[ameligrana]

Very nice! It seems to work pretty well.

I found some issues though when using with "LU" and "MT" with the code

import BeforeIT as Bit

for country in Bit.AVAILABLE_COUNTRIES
	try
		co = Bit.download_zenodo_calibration_object(country)
		parameters, initial_conditions = Bit.get_params_and_initial_conditions(co, Bit.DateTime(2020, 03, 31);
		    scale = 1 / 1000)
		model = Bit.Model(parameters, initial_conditions)
		Bit.step!(model)
	catch e
		println(country)
		println(e)
	end
end

the stepping throws with InexactError(:Int64, (Int64, NaN)). I did some brief debugging and I found that parameters["alpha_s"] has some zeroes, and this is in turn due to output in get_params_and_initial_conditions being 0 for some sectors, which is strange. Maybe though this is actually a problem in the model, not the calibration, which can't deal with this initial conditions, given that those countries are very small, they could be true zeroes.