Remove duplicate code
Fix wrong comment
Extract function parsing Y,m,d,M,h,s 6-tuple function arguments
Use gmtime to calculate date offsets instead of doing it manually
zero-initialize tm struct before filling
Don't call mktime(3) twice on the same struct tm
Comment tm_year use (-1900 bias)
Merge pull request #1206 from dottedmag/refactoring/no-manual-date-handling

Refactoring/no manual date handling