Update readme for building on macOS

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Homebrew provides glew and libdeflate

(Maybe closes #89)

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Steps needed to compile on macOS:

• Add #include <stddef.h> to utils.h (Make it so CMake now grabs the latest dr_wav version instead of 0.8.1 #105)

• Currently, only part of the server list is rendered:

  

  A workaround for this is commenting out these lines in hud.c:

   glEnable(GL_SCISSOR_TEST);
   glScissor((settings.window_width - 600 * scaley) / 2.0F, 50 * scaley, 600 * scaley, (430 - 50) * scaley);
  

  and this line:

   glDisable(GL_SCISSOR_TEST);
  

  This workaround results in this behavior when scrolling:

  

[xtreme8000]

Currently, only part of the server list is rendered

This happens because the actual window size is different from what the game thinks it is, try adjusting your window dimensions in settings.

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Strangely, it seems multiplying each parameter of glScissor by 2 fixes the problem:

   float scissor_x = (settings.window_width - 600 * scaley) / 2.0F;
   float scissor_y = 50 * scaley;
   float scissor_w = 600 * scaley;
   float scissor_h = (430 - 50) * scaley;

#if __APPLE__
   scissor_x *= 2;
   scissor_y *= 2;
   scissor_w *= 2;
   scissor_h *= 2;
#endif

   glScissor(scissor_x, scissor_y, scissor_w, scissor_h);

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Bug with picking up intel:

Before:

After:

[xtreme8000]

possibly related to #145 and #146