Bugs in the Baháʼí calendar around Ayyam-i-Há and around Naw-Rúz

[pfo]

Thank you for this project, I have found it very useful and appreciate your work.

In the Baháʼí calendar, I have found some bugs and hope that they can be fixed in future versions. The day of the month is sometimes 0 or lower, or 20 or higher, with the minimum day number being 1 and the maximum being 19.

Examples around Ayyam-i-Há:

>>> from convertdate import bahai

>>> bahai.format(*bahai.from_gregorian(2017, 2, 28)) # should be 4 Days of Há 173
'0 Loftiness 173'

>>> bahai.format(*bahai.from_gregorian(2016, 2, 28)) # should be 3 Days of Há 172
'-1 Loftiness 172'

>>> bahai.format(*bahai.from_gregorian(2020, 2, 27)) # should be 2 Days of Há 176
'-2 Loftiness 176'

>>> bahai.format(*bahai.from_gregorian(2028, 2, 26)) # should be 1 Days of Há 184
'-3 Loftiness 184'

>>> bahai.format(*bahai.from_gregorian(2096, 2, 6)) # should be 1 Dominion 252
'-22 Loftiness 252'

Examples around Naw-Rúz (New Year):

>>> from convertdate import bahai

>>> bahai.format(*bahai.from_gregorian(2025, 3, 20)) # should be 1 Splendor 182
'20 Loftiness 181'

>>> bahai.format(*bahai.from_gregorian(2092, 3, 20)) # should be 2 Splendor 249
'21 Loftiness 248'

>>> bahai.format(*bahai.from_gregorian(1927, 3, 21)) # should be 1 Splendor 60
'0 Splendor 60'

>>> bahai.format(*bahai.from_gregorian(1960, 3, 20)) # should be 19 Loftiness 116
'20 Loftiness 116'