Feature: Add support for calendar years, calendar months and more

[jufemaiz]

• Supports inclusive vs exclusive date ranges
• Respects timezones
• Correctly calculates differences over leap years (does not assume 365.25 days
  in a year or 30.42 days in a month)
• Correctly corrects for daylight savings
• Support for in_calendar_years and in_calendar_months for monthly and yearly
  billing cycle calculation support
• Use of rounding as an option rather than hardcoded 2 (set as default option to prevent breakage)

[jufemaiz]

Ref:

• Inclusive dates #29 – inclusive date ranges (n/a for times)
• #in_months doesn't seem to respect months having different days #39 – varying numbers of days per month

[jufemaiz]

bump

[bmoelk]

 > TimeDifference.between('Oct 21, 2017'.to_time, Time.now).in_years
 => 1.45 

IMO: Please rename your fork (https://github.com/IQTHINK/time_difference) and become the maintainer. This gem appears to be abandoned. 9 open PR's 😞