This reverts commits 54fd8176d7, 4c5becb6b1 and 8f578150e.
Those kind of commits must be reviewed and approved by project owners.
That one:
* Broke Collada building by not properly updating all calls to modified
function.
* Broke *whole* ID management by not properly updating library_query.c.
And in general, I am strongly against backward ID pointers, those are
*always* a serious PITA for ID management. Sometimes they cannot be
avoided, but in general other ways to get that kind of info should be
investigated first.
e6f3d8b3e1