Diffuse radiation error when simulating over 1 year

[EttoreZ]

This issue is to address an error in the calculation of the Diffuse radiation, that happens because of the model Buildings.BoundaryConditions.WeatherData.BaseClasses.EquationOfTime when trying to simulate over 1 year or 365 days. In particular in an auxiliary equation for the calculation of the equation of time:
Bt = Modelica.Constants.pi*((nDay + 86400)/86400 - 81)/182
The variable nDay should be within the boundary 0<nDay<365. Now instead it varies according to the simulation clock time so from 0 to potentially beyond one year. A possible solution to have consistent years is to keep nDay always between 0 and 365. Below you can find a table reporting the values of eqnTim being different by simulating 600 seconds starting at year 0 or starting at year 1.

sim time	eqnTim start =365	eqnTim start=0
0	-4.0536275	-3.6068733
30	-4.053782	-3.6070292
60	-4.0539365	-3.6071851
90	-4.0540905	-3.607341
120	-4.054245	-3.607497
150	-4.054399	-3.607653
180	-4.0545535	-3.6078086
210	-4.054708	-3.6079645
240	-4.054862	-3.6081204
270	-4.0550165	-3.6082764
300	-4.0551705	-3.6084323
330	-4.055325	-3.6085882
360	-4.0554795	-3.6087441
390	-4.055634	-3.6088998
420	-4.055788	-3.6090558
450	-4.055942	-3.6092117
480	-4.0560966	-3.6093676
510	-4.056251	-3.6095235
540	-4.0564055	-3.6096795
570	-4.0565596	-3.6098354
600	-4.056714	-3.6099913

[EttoreZ]

This issue is solved by PR1722