Allow passing `special_flags` to `Group.draw`

[MarcellPerger1]

Description
Add a special_flags argument to Group.draw (and all the other group classes).
This would be useful as with this feature, I could write code like this:

group.draw(surface, special_flags=pygame.BLEND_RGBA_MAX)

instead of

for s in group.sprites():
    surface.blit(s.image, s.rect, special_flags=pygame.BLEND_RGBA_MAX)

Also, for more complicated group classes (eg. RenderUpdates), you have to copy the entire code of the .draw functions and change just the line where the .blit method is called which is quite annoying.

See pygame/pygame#3719 for the issue I opened over there (before I found pygame-ce).

[JoKing-1999]

Good idea, thanks for pointing it out. For someone who will try to implement i, try to see if https://pyga.me/docs/ref/surface.html#pygame.Surface.fblits could be used. Also, I think droid is modifying sprite atm, so maybe then we can implement this as well

[aatle]

The reason why fblits() could not be used currently is because it does not give back a rect of the changes.

This feature should be easy to implement though.

[Starbuck5]

Honestly I wouldn't think this should be added, it's extra API for a niche use, could be accomplished by overloading draw (I think?), and philosophically I think sprites should be responsible for how they are drawn, not what group they are in.

However, since you've gotten this added to pygame/pygame, and we would like to be compatible with pygame/pygame, I guess we should do it.

@MarcellPerger1 Would you like to open a PR?

[MarcellPerger1]

Yes, I'm happy to open a PR when I have a bit of time (probably this weekend)