Complete Overhaul + Hermite Splines!

Breaking Changes: this update is not compatible with older versions of this library!

• Added the missing "AddCurveRight" override in the HermiteSpline class.
• Initial setup initialization in all sample controls.
• Added a new PolygonTextureTest spline and texture called "RaceTrack.json" (CatMulRomSpline) and "roadTexture.png" (Texture2D).
• Added more possibilities of showing or hiding specific elements of a spline (Lines, Points).
• The selected tangent text is now drawn directly inside the HermiteSplineControl instead as a forms label.
• The game project now includes spline json data generated with the revised MonoGame.SplineFlower library update. It defaults to the HermiteSpline test now and loads it as an xnb file with the ContentManger to show that it can handle the latest additions and changes to the library and the pipeline.
• Updated the samples project to work with the new MonoGame.SplineFlower update.
• Based on the revised library update the MonoGame.SplineFlower.Content.Pipeline library now reflects the latest changes and additions.
• New spline type: HermiteSpline! (basically a CatMulRomSpline but with "Bias" & "Tension" parameters as well as moveable Tangents, which gives more precise control over the curve of this spline.
• Complelty revised the MonoGame.SplineFlower library and gave it more structure and encapsulation, which makes it way easier now to understand and use the library as well as adding new spline types.
• Updated AssemblyInfo
• Solution upgraded to support Visual Studio 2019