Adding MSAA

[Mykola Hordynchuk]

I tried to enable mssa using sampleCount = 4 for both the MTKView and the pipelinestatedescriptor,
but I had to switch the empty texture to type2DMultisample. As a result, metal debugger says that fragment_target function wrong, because we use texture2d

Can any help me with this? Thx

[Harley]

Mutisample is currently not supported

[Mykola Hordynchuk]

@Harley-xk is any chance to enable antialiasing? all drawing strokes looks not good when we zoom out.

[Harley]

@0-mykola All code about textures and sampling needs to change from the bottom. It's a big project, so ... there's no plan now.