implement loading Tiled Point objects

[happy-bracket]

This pull request adds Tiled Point objects (https://doc.mapeditor.org/en/stable/reference/tmx-map-format/#point).

As of now, TmxMapLoader parses points into rectangles with zero width/height. This behavior is probably fine as it is, but one could argue that it's counter-intuitive and non-explicit, so, here we are.

It's also a breaking change for all the people who rely on that their points are parsed into zero-sized rectangles. So, if this PR has any value, I'm open to suggestions on how to work around that.

TiledMapObjectLoadingTest is updated to reflect a new type of objects.

[SimonIT]

You have to add the PointMapObject to this file for gwt:

libgdx/gdx/res/com/badlogic/gdx.gwt.xml

Lines 296 to 303 in 3d1f76f

	<!-- maps/objects -->
	<include name="maps/objects/CircleMapObject.java"/>
	<include name="maps/objects/EllipseMapObject.java"/>
	<include name="maps/objects/PolygonMapObject.java"/>
	<include name="maps/objects/PolylineMapObject.java"/>
	<include name="maps/objects/RectangleMapObject.java"/>
	<include name="maps/objects/TextureMapObject.java"/>

[happy-bracket]

@SimonIT fixed, thank you

[mgsx-dev]

Could you please fix formatting, indentation seams off. You can use provided formatter, see contribution guidelines.
You also need to update CHANGES file with this API addition.

Apart from these details, it looks good to me.

[mgsx-dev]

could you please fix formatting here as well :-)

[mgsx-dev]

I think it's good to have it but considering it's a breaking change without much value for now, i propose to merge it when we will implement some other big changes related to Tiled 1.x (eg. infinite map support, template support) and/or a new major version of libGDX.