Pixel format fixes.

Changelog:

• Added libmulti_set_gms2_pixel_format and libmulti_get_gms2_pixel_format to toggle GMS 2 pixel format behavior.

How to use

• GM:S 1.4 users: Import the libmulti.gmz project and look at the sample object.
• GMS 2.2.5 users: Import the libmulti.gms2.yyz project and look at the sample object.
• GMS 2.3.1+ users: Import the libmulti.gms23.yyz project and look at the sample object.

How to integrate into your own game

This implies you've already imported and tinkered with the sample project. (oh and also read the docs a bit)

• Load your game project.
• Right click at Extensions then click Add Existing
• Then in the opened up file dialog, navigate to the extensions folder in the sample libmulti project
• And then choose the libmulti.extension.gmx file if you're using GM:S 1.4 or the libmulti.yy file if you use GMS 2+.
• A new extension called libmulti should be added, then you're good to go!

How to update the extension

• Load your game project.
• Right click on the libmulti extension, then click Delete and agree.
• Re-add the new extension (see How to integrate into your own game).
• Try running your game again, if all went fine, have fun.