Add draw.aaline width argument

[mzivic7]

This PR adds width argument to draw.aaline.

How it works:
First draw draw_line_width (its not antialiased).
Calculate its corner points, but slightly move them so relevant antialiased pixels don't overlap with fully opaque pixels.
Then draw 2 thin draw_aaline.

I made this calculation in separate function line_width_corners, because it will be used again when implementing width for draw.aalines and draw.aapolygon.

Sample code

import pygame

pygame.init()
screen = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()
run = True
while run:
  for event in pygame.event.get():
      if event.type == pygame.QUIT:
          run = False
  screen.fill("black")
  pygame.draw.aaline(screen, "white", (120, 100), (220, 160), 16)
  pygame.draw.aaline(screen, "red", (180, 170), (100, 260), 16)
  pygame.draw.aaline(screen, "blue", (70, 240), (150, 150), 7)
  pygame.display.flip()
  clock.tick(60)
pygame.quit()

[bilhox]

LGTM, big thanks for this work!

It will just need a little update with upstream and test fixes.

[bilhox]

Actually I forgot something important, the final step is also to add new unittests.

[damusss]

Actually I forgot something important, the final step is also to add new unittests.

well also perhaps it'd be nice if there weren't 15 failed checks lmao

[bilhox]

Judging by how much line got updated/added, I'm moving this PR to 2.5.2 milestone.

[bilhox]

LGTM

[damusss]

Awesome, thank you :) LGTM 👍
Looking forward for aalines, polygon, and aapolygon width enhancements (especially polygon, bro is really ugly at the moment)

[MyreMylar]

OK, LGTM. Line output looks good in local testing and the code makes sense.

👍 🎆 🍾