Fix msg_date_d and msg_date_e wrongly parsing dates after 29 Feb. Mon returned by month_d() is in 0..11 range. Fix unit-tests that were assuming 25 Mar 2004 to be Wednesday but it's actually Thursday.

Fix msg_date_d and msg_date_e wrongly parsing dates after 29 Feb. Mon returned by month_d() is in 0..11 range. Fix unit-tests that were assuming 25 Mar 2004 to be Wednesday but it's actually Thursday. #54