Remove the unlock for masonry.  I forgot that it's staffed by peasants, oops.
Instead of marking all messages as read every time we end a turn with the messages data open, mark all but 10 as read.  Allow the player to close and reopen buildings from Interface::building_status().  Move setting that function's help text to its own function.
Fix some hiccups with opening/closing via the buildings interface.
Tweak.
Reopen the "open" property from Area and move it to Building.
Fledgeling start of city AI.