Added a StrBuf that will eventually contain all of the

Added a StrBuf that will eventually contain all of the
miscellaneous javascript that any page needs.  Callers should be appending
script code to the trailing_javascript strbuf instead of embedding it in the middle
of the page.  This will cause it all to be executed at once, which is
the recommended practice.  I haven't moved anything to this yet because
I think the script still isn't executing.