add vecdeque! using with_capacity

[Nokel81]

Fixes: #10

[Boscop]

@Nokel81 Thanks! Could you also support this syntax? vecdeque![expr; N] Like slice-deque's sdeq macro:

let v = sdeq![Rc::new(1_i32); 5];

[bluss]

@Boscop Can I invite you to help with maint of this crate? Fair warning - I don't have much time for Rust, but in my accounting books, this crate has been in maintenance mode. If you want, let's also set up crates.io publishing for you.

I'd suggest to keep existing users in mind, being careful with changing the scope of the crate and only aiming for semver breaking changes with very good reason. Let me know what you expect from me.

[minghu6]

Hope for your merge @bluss

[gmoshkin]

Hey guys, anybody wants to merge this anytime soon? I'd really like to use this in my work!

[praveenperera]

@bluss can we merge this in? I can help maintain this crate

[boredcity]

Any news on that one? 🙏

[willtennien]

Can you submit the same PR to github.com/willtennien/maplit2? I'll try to approve speedily.