Datetime input reloaded

Ok, another try:
- localized
- clear button
- time in 24h or 12h format
- datepicker opened with button
- simplified/unified datetime input macro
- gobal bolt variable now usable

Todo:
- buttondesign - someone how knows bootstrap can do
- a little bit optimizing
- setting error on wrong dates
- pattern
Would be nice if someone used to 12h system could test.

PS: You can make the hidden field visible for debugging purpose by setting true [here](https://github.com/bolt/bolt/pull/2150/files#diff-9909a6029923d5b0280d930bb59a9cd5R118)