Replace call_user_func_array(), part 1

Replace call_user_func_array(), part 1

Uses new PHP 5.6 syntax like ...parameter unpacking and
calling anything looking like a callback to make the code more readable.
There are much more occurrences but this commit is intentionally limited
to an easily reviewable size.

Change-Id: Idcec077ef3fdf029b632cceafd0150851ad723e3