49 - allow read_index_with_flags for memory mapping some index types

[mooreniemi]

I think using pub mod consts here achieves least surprise for users and minimizes boilerplate to make enum like a bitmask. (There's this crate, and this crate, but it seems a lot just to make enum have something like impl BitOr / allow for "and"ing options.)

I could attempt to test this by creating a temporary index file and open it with these flags, too.

Not sure if you'd really want to version bump on this.

[Enet4]

Thank you for the pull request. Please see the concerns inline. I suspect some parts were not written to completion.

[mooreniemi]

Hi just bumping on this. I responded to your comments and can't proceed without more feedback.

[Enet4]

Right, please look into the duplicate definition problem and see if you can incorporate the IoFlags newtype. With that done, I think this would be ready to enter.

[mooreniemi]

Sorry for delays, and thanks very much for your feedback, was great to learn proper way to do the BitOr here.

[mooreniemi]

Do you think this can go up as a new crate version in the next week? I'd like to take a dependency on this functionality soon.

[Enet4]

Yes, a new crate version is due. I'll look into this. Thank you for your contribution!