macroscript 0.6.0

A reimplementation of my macroscript programming language.
Documentation
# macroscript
---
This is a full reimplementation of [Robot Is Chill](https://github.com/balt-dev/robot-is-chill)'s macro-based programming language.

## Changes
A few things have been changed between RIC's implementation and this one.
The most notable ones include:
- Numbers are limited to f64s (no complex numbers)
- No runtime limits
- More builtin macros (check the docs!)
- Text macros (e.g. `double: [multiply/$1/2]`) aren't included by default
  - In order to use text macros, they have to be added using `TextMacro`.

## Example
```rust
use macroscript::{apply_macros, add_stdlib};
use std::collections::HashMap;

fn main() {
  let mut macros = HashMap::new();
  add_stdlib(&mut macros);
  
  let input = "[add/5/3]".to_string();
  let result = apply_macros(input, &macros).unwrap();
  assert_eq!(result, "8");
}
```