Add support for sending the browser to MAFF when appropriate, allowing more featureful MAFF saving.

By giving the browser to the MAFF creation code, extra metadata can be saved in the MAFF file, such as back/forward history and viewer position.  We only want to give the browser in the case where we want to save the whole page.  For partial saving, such as clippings, we must not pass in the browser.

Currently this is only implemented for the autoshelving feature.  It should probably be done for all whole page saving.