Import Picking and placing single houses in scenario editor patch

Minor whitespace fixes

http://www.tt-forums.net/viewtopic.php?f=33&t=68894&view=unread#p1099696

src/command_type.h

@@ -187,6 +187,7 @@ enum Commands {
 	CMD_REMOVE_SIGNALS,               ///< remove a signal
 	CMD_TERRAFORM_LAND,               ///< terraform a tile
 	CMD_BUILD_OBJECT,                 ///< build an object
+	CMD_BUILD_HOUSE,                  ///< build a house
 	CMD_BUILD_TUNNEL,                 ///< build a tunnel
 
 	CMD_REMOVE_FROM_RAIL_STATION,     ///< remove a (rectangle of) tiles from a rail station