XCLASS tslib_fe so that in the page cache respects starttime and endtime of tt_content elements on that page.
The function tslib_fe->setPageCacheContent is replaced by this extension.
The extension gets the expire-timestamp which is configured by TypoScript etc.
If there is an tt_content element on that page (which is not hidden and not
deleted) the starttime and the endtime will be checked now too.
If there is a starttime or an endtime which is between "now" (Rendering time)
and the expire-timestamp, the expire-timestamp will be set to that time.
Internally the expire-timestamp is checked everytime a page is requested.
If the page is in the cache and not expired, than the cache will be taken.
And without this extension, the starttime and endtime of the content elements
have no influence.
It checks only tt_content elements on that page.
It is not tested with versioning or workspaces.
Feedback is welcome.