discuss: spanned AST

[0xaatif]

@Nashtare you were curious about the work required to get more IDE integration.

I think this is the cheapest way to get where we want - do note the non goals as things that can't be achieved by the current design.

I reuse Rust's lexer, and the syn parsing framework.

ast2.rs replaces the following files:

• evm_asm.pest
• ast.rs
• parser.rs

Worth getting a sizing from you as to how to make the rest of the interpreter/compiler work with the new frontend.

Part of investigation for #299

[0xaatif]

oops :^)