fix some typo in comments

Add support for a YubiKey vendor extension to retrieve public metadata
(including the public key, PIN/Touch policies and whether or not the key
was hardware generated) for a given key slot.

Also use this new method to determine the pin policy, for YubiKeys that
support it. This is more general than using the attestation certificate,
as it also works for keys that have been generated offline and imported
into the hardware token.

Fixes #129

…mand.

Following instructions under https://go.dev/blog/v2-go-modules

…ting them. Prefer AES192 over 3DES when possible.

Update supportsVersion to use *version and bytes instead of Version and ints to eliminate a lot of unnecessary calls to .Version()