Add a function to load an OBJ mesh with texture

[0x177]

a comment on the top of model.rs mentions loading models, but there isn't any code that does that, so i added it. this function is probably slow and i don't like the tobj dependency, but it is easy and less bloated than other obj parsers.

Blender monkey with brick texture applied

[not-fl3]

Hi, thanks for PR!

Tho I am not quite sure if this code justify adding an extra dependency - user can always use tobj directly, its not that much code to get tobj data into macroquad's model.
And, lets be honest, macroquad is not really very good for 3d anyway, so making every single user to compile tobj all the time might be a bit of an overkill here.

[0x177]

Hello!

i agree. only vertices are used here so it would be pretty easy to add a small parser, but considering macroquad's 3d capabilities, it realistically wouldn't be used by anyone (plus it is easy to just use tobj as you said).