New Section: Drawing Shapes

I wonder if there's a more efficient way to create vertices:

var vertices = new Array<FlxPoint>();
vertices[0] = new FlxPoint(0, 0);
vertices[1] = new FlxPoint(100, 0);
vertices[2] = new FlxPoint(100, 300);
vertices[3] = new FlxPoint(0, 100);
---
Changes mentioned

* Added FillStyle and LineStyle instead of Dynamic (also worked btw)
* Added Unique param on makeGraphic() and note about it
* Linked docs of `using` keyword
Merge pull request #66 from AndreiRegiani/patch-1

New Section: Drawing Shapes