(#10, #32) Add outline rendering to Polygon2D

With the addition of outline rendering, the boolean determining fill or outline was no longer satisfactory.
As such, the `RenderStyle` class was created, defining the different options for rendering (Only `Polygon2D` has this so far, but it will be rolled out to other classes as needed.)

Additions
- `Polygon2D#renderStyle` - the replacement to the aforementioned boolean which determines if objects should be filled, outlined, or both. Corresponding default is `Polygon2D#DefaultRenderStyle`.
- `Polygon2D#outlineStroke` - the `java.awt.BasicStroke` representing the style of the outline. Corresponding default is `Polygon2D#DefaultStroke`.
- `Polygon2D#outlineColor` - the `java.awt.Color` representing the color of the outline. Corresponding default is `Polygon2D#DefaultOutlineColor`.

Breaking Changes
- Removed all but one `Polygon2D` constructor and made it package private
    - Included are `create` methods that call on a `Polygon2DBuilder` class which will be added in the next commit. This will replace the excessive amounts of constructors that would have eventually arisen.
- Removed `Polygon2D#DefaultFill` and `Polygon2D#shouldFill`, in accordance with the information at the beginning of the commit message.
- Renamed `Polygon2D#get/setPaint` to `get/setFill`

Removals
- Removed transform information from `Polygon2D#toString`
- Removed `Polygon2D#DefaultShow`

src/example/java/tech/fastj/example/bullethell/scripts/PlayerCannon.java

@@ -51,8 +51,9 @@ private void createBullet(GameObject player) {
         Pointf cannonFront = Pointf.rotate(startingPoint, rotationAngle, rotationPoint);
         Pointf[] bulletMesh = DrawUtil.createBox(cannonFront, BulletSize);
 
-        Polygon2D bullet = (Polygon2D) Polygon2D.fromPoints(bulletMesh)
-                .setFill(Color.red)
+        Polygon2D bullet = (Polygon2D) Polygon2D.create(bulletMesh)
+                .withFill(Color.red)
+                .build()
                 .addBehavior(bulletMovementScript, gameScene)
                 .<GameObject>addTag(Tags.Bullet, gameScene);