Feature/text

[gustavo-tomas]

Adding smooth anti aliased text (with multiple SDF channels). I still didn't manage to make it perfect like the msdf examples, but it is good enough in most use cases.

Some features/fixes we would like to implement:

• Fix msdf gen submodule. For now the submodule points to the original repo. We changed some files in that repo so we need to create a fork before merging.
• Add freetype lib. The msdf gen uses freetype to load fonts. We should also package freetype.
• Convert font into a resource. For now it is a standalone class, but we would like to keep it as a resource like textures and models.
• Create TextComponent. We need to integrate the text into the ecs. This also include component serialization/deserialization.
  • TextComponent struct
  • Serialization/Deserialization
• Create Text UI. Besides the component, it would be nice to have a text box in the editor to type out some text and see it live.
• Cache generated font atlases. Right now we generate an atlas for every font every time we load them. Ideally we should save the generated font atlas into a .png or binary (maybe with a pretty big resolution) and simply load it.
• Optimize text rendering. Right now performance is pretty bad. It would be amazing if we could batch some draw calls before rendering it.

Fixes #68