BrainFuck compiler using Rust proc macro

More precisely, the BrainFuck-to-Rust transpiler using Rust proc macro

Examples:

1. Runs on into called (using into method to obtain (pc: usize, mem: Vec<u8>))

   let (pc, mem) = brain_fuck!(
       ++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.
       >---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.
   ).into();
   println!("{:?}", (pc, mem));
   

2. Runs on env called (env method sets pc and mem for the block) (env method also returns (pc: usize, mem: Vec<u8>))

   let mut pc = 0;
   let mut mem = vec![72, 101, 108, 108, 79, 119, 104, 97, 116, 65, 115, 10, 0];
   let (pc, mem) = brain_fuck!(
       [.>]
   ).env(pc, mem);
   println!("{:?}", (pc, mem));
   

3. Runs on drop

   brain_fuck!(
       ++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.
       >---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.
   );