[ticket/11800] Remove forum_fn from memberlist_search.html

PHPBB3-11800
[ticket/11800] Fix JavaScript in simple_footer.html

Include forum_fn.js via INCLUDEJS
Move $SCRIPTS after footer event, allowing extensions to include scripts
Use correct template variable for including scripts

PHPBB3-11800
[ticket/11800] Fix scripts variable in subsilver simple_footer

PHPBB3-11800
Merge remote-tracking branch 'cyberalien/ticket/11800' into develop

* cyberalien/ticket/11800:
  [ticket/11800] Fix scripts variable in subsilver simple_footer
  [ticket/11800] Fix JavaScript in simple_footer.html
  [ticket/11800] Remove forum_fn from memberlist_search.html