New tag version of datetimepicker avoids hanging some browsers

But still won't work with those same browsers.
Devel versions seem to work, but I chose to be conservative.

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Regarding:
https://zothub.com/channel/one/?f=&mid=0e8a782996187cc4860c621c5bc2994326b21c8b24b907d465308ea5f3134fa2@zothub.com