since middle is not seprate from out we are now keeping all way tags in middle (ie sans filtering) that means that when an out gets at a way through the middle it cant expect its particular important tags to be the only ones there. therefore each out must filter using its own transform/export list before using a way
Merge remote-tracking branch 'MapQuest/kk_multiback' into mla_multi_backend
Account for pending ways and relations in iteration.
Add pending accounting to middle-ram.
Rate limit the `finish` method so that progress can be printed.
Fixed bug in middles due to incorrect checking of `finished` flag.
Fixed tests for changes in middle callback interface.