build jok's own basic types

[Jack-Ji]

In order to make code more improvable/readable, jok should use it's own basic types, instead of relying on SDL2.zig's wrappers everywhere. Here's checklist:

• change from sdl.Window to jok.Window
• change from sdl.Event to jok.Event
• change from sdl.Renderer to jok.Renderer
• change from sdl.Texture to jok.Texture
• change from sdl.Vertex to jok.Vertex
• change from sdl.PointF to jok.Point
• change from sdl.RectangleF to jok.Rectangle
• change from sdl.Size to jok.Size