[website, feature-request] On /all page, show downloads per month

[uvtc]

On https://lib.haxe.org/all/ is the "Downloads" column displaying total downloads, downloads per year, or something else?

I think it would be most helpful to users if the default were to show downloads per month, or maybe per 3 or per 6 months. (Perhaps there could still be a link to still see total downloads, since some may still want to look at that.)

While it's nice to see big numbers of downloads, I think that downloads/last-month (or even last 6 months) would give a better indication of the libraries most currently in use.

[uvtc]

See @markknol 's closing comment at #216 and pull #417 .

Also, I didn't realize that all libs have an "All Versions" tab containing a beautiful plot of downloads by date (I think the vertical axis is total cumulative downloads), plus below shows the downloads per release. Lots of useful info in there.

[markknol]

We currently only track downloads per version, downloads per month/day/year require this PR #432