Create a hook for custom relative date filters (CRM-16195)
To summarize: From the time relative date filters debuted in 4.2(?) until 4.7, each release added a number of relative date filters that one person needed and the rest of the world didn't. To prevent this happening forever, we moved relative dates into an OptionGroup, and intended to give the ability to create new ones.
I worked on this last year but some cleanup PRs got stalled. They're all merged now so I'm submitting this.
While @eileen did work recently to support relative dates like "32 months in the past", it's still not possible to do relative dates like, "from 6 months ago to the end of this year", or "from Thanksgiving to Christmas". A former client of mine had reports that went from October to September, but this was NOT their fiscal year.
A simple hook facilitates the creation of custom relative date filters. I'll submit tests, but you can see an extension that uses it here: https://github.com/MegaphoneJon/com.megaphonetech.relativedatetest