toql 0.1.2

# Concept

Toql is a set of crates that aim to simplify web development:

1. A web client sends a Toql query to the REST Server.
2. The server uses Toql to parse the query and create SQL.
3. SQL is send to the database.
4. The database results are sent to the client.

The Toql provides high level functions for prodctivity and low level functions to handle edge cases.

## Example

Here is part of a code that uses Rocket to serve users from a database. 

```rust
	#[derive(Toql)]
	#[toql(skip_indelup)] // No insert / delete / update functionality
	struct Country {
		id: String,
		name: Option<String>
	}

	#[derive(Toql)]
	#[toql(skip_indelup)]
	struct User {
		id: u32,
		name: Option<String>,
		#[toql(sql_join(self="country_id", other="id"))]
		country: Option<Country>
	}
    
	#[query("/?<toql..>")]
	fn query(toql: Form<ToqlQuery>,  conn: ExampleDbConnection, 
		mappers: State<SqlMapperCache>) -> Result<Counted<Json<User>>> {
		let ExampleDbConnection(mut c) = conn;

		let r = toql::rocket::load_many(toql, mappers, &mut c)?;
		Ok(Counted(Json(r.0), r.1))
	}

	#[database("example_db")]
	pub struct ExampleDbConnection(mysql::Conn);

	fn main() {
		let mut mappers = SqlMapperCache::new();
		SqlMapper::insert_new_mapper::<User>(&mut mappers);

		rocket::ignite().mount("/query", routes![query]).launch();
	}
```

If you have a MySQL Server running, try the full CRUD example.

```bash
ROCKET_DATABASES={example_db={url=mysql://USER:PASSWORD@localhost:3306/example_db}} cargo +nightly run --example crud_rocket_mysql

```