Tiled 0.7.1 released

Shortly after we released Tiled 0.7.0, a number of issues were found. Some of them were pretty critical or meant basic functionality was broken, so I decided not to wait too long with making a new release. The changes:

• Added support for a margin around a tileset image
• Improved the tileset manager and allow tileset reorganizing (by Jared Adams)
• Fixed automatically adding extension to tileset Save As... dialog
• Fixed saving/loading of layers with an origin other than 0,0
• Fixed map resize to apply the offset to layers not matching the map bounds
• Fixed loading of object group properties
• Fixed duplicates of object groups to not share the objects
• Fixed Lua export to increase firstgid of tilesets properly (by Jelle Geerts)
• Fixed saving of property values that contain quotes
• Fixed the state of menu actions when starting up without a map