Particles data driven (#388)

* yay, a start on data driven particles

* added data driven support for all particle profiles

* pretty much finished all of the particle serialization code

* resolved an inconsistency with the interpolators

Source/MonoGame.Extended.Particles/Modifiers/VortexModifier.cs

@@ -6,6 +6,7 @@ namespace MonoGame.Extended.Particles.Modifiers
     {
         // Note: not the real-life one
         private const float _gravConst = 100000f;
+
         public Vector2 Position { get; set; }
         public float Mass { get; set; }
         public float MaxSpeed { get; set; }