why no_std and no_main

[bestman8]

when i tried this a few days ago it didn't have those changes so is there any reason why.
imo this is kinda confusing like can i just remove those or do things break when i remove them.

talking about these in main.rs

#![no_std]
#![no_main]

#[no_mangle]

[ivmarkov]

Thanks for noticing!
These were forgotten since the last change to the template that simplified it (who uses the template without STD?).

I've fixed it now.