(self, os, title, body, headextra, view)
Called to output the view header to the given output stream.
@param os a file-like object (use os.write())
@param title the title of this view
@param body the body tag, which may contain extra parameters such as
onLoad scripts, and may also be empty eg: for the frames index
@param headextra extra html to put in the head section, such as
scripts