Rendering pipeline rework

[Apostolique]

The current way of rendering components isn't all that efficient. The scissor rect handling requires flushing the batch between each components. We're using the SpriteBatch which doesn't support drawing shapes natively without hacks. Font rendering is done with FontStashSharp, it would be nicer to use MSDF for example MonoGame.MSDF-Font-Library.

In the long term, it would be nice to support fancy effects for example check the UI in Frostpunk. It's possible to do something like that already but it would be really painful.

Some features to think about:

• CPU cropping directly on the vertices. (Avoids needing scissor rects.)
• MSDF font
• Shapes, maybe with a simplified version of Apos.Shapes.
• Masking

Ideally you can have cleaner batches.