AbstractBuildForm.php: new function subrecordHead(). Replaced several hard coded subrecord column names against constants.

# Conflicts:
#	javascript/src/QfqForm.js

Feature: Upload Button - wrapped with Bootstrap Button - reverted to old style, delete/refresh behaviour broken with bootstrap style

#4606 / _link: qualifier to render bootstrap button - add tooltip to button/text, even if there is no link

#4606 / _link: qualifier to render bootstrap button - implement token  'b:...' for link class. Manual is updated. Open: `pageX` should be recoded to use the new 'b:' instead of hardcoed behaviour to render a button.

Feature: Upload Button - wrapped with Bootstrap Button. New option 'fileButtonText' to specify a button text.

Feature #3752 / Pills auf mode|modeSql=hidden|readonly setzen - implemented during 'form load' (not dynamic update)

* Broken Redirect after Save - fixed
* Broken same HTML ID for FE copies in a template group. - fixed

Bug #4548 /Template Group: 'form-update' broken - max tg element value/index shown after save instead of last user supplied value, but save is ok.
Neu wird nach dem Speichern das Formular nochmal komplett geladen. Das ist wichtig um die durch aftersave geaenderten Records in die Formularelemente zu bekommen.