kill all at_top_of_body()

Convert all legacy at_top_of_body(); these constructs are discouraged because all JS should be done in footer through one of these:
1/ YUI events
2/ $PAGE->requires->js_init_code()
3/ $PAGE->requires->js_function_call()

it is recommended to use external YUI modules $PAGE->requires->js_module() libraries instead of $PAGE->requires->js()