ContentNode.layout_header(): Tidy, including removal of a bunch of residual variables and organizing the remaining ones for clarity. Also, indicate why the heck we're recloning the page every time.
ContentNode.layout_header(): Tidy, including removal of a bunch of residual
variables and organizing the remaining ones for clarity. Also, indicate why
the heck we're recloning the page every time.

Remove ContentNode.prototype.include_my_page(), putting the functionality
directly in ContentNode.prototype.my_page$().

SpiderOak/so_client_html5,SpiderOak/so_client_html5