Add some unsafe magic for minimal optimizations, add .idea to .gitignore and fix some typos

[Kleinmarb]

Thanks for the amazing contribution to open source url parsing!

I am using this lib right now and thought that I should look into it a bit, I ended up doing minor changes.

I understand if the unsafe code gets rejected, but I even left some safety comments.

[anonrig]

Also can you fix clippy errors?

[Kleinmarb]

I added tests and comments that illustrate which number maps to which enum variant.

Regarding the clippy errors, I don't get any.

Now let's talk about performance: If I'm honest there will be a performance difference but it will be negligible. But the code I wrote is 100% safe, you can trust me on that one since I added a#[repr(u32)] on the enum which allows for safe transmution between value as u32 and the enum as long as value is not bigger than the number of variants of the enum -1, but we check for that.

If you still think its risky, just deny the commit, it's alright for me.

[Kleinmarb]

Oh ok I should have done the assembly check myself. Thanks for pointing out that it produces the same exact instructions.