Layout changes needed for iPhone X

[hipwelljo]

[x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
[x] I've read and agree to the Code of Conduct.
[x] I've searched for any related issues and avoided creating a duplicate issue.

Description

For iPhone X, elements need to be repositioned to avoid being underlapped by the home button indicator and the rounded corners. Largest issues I see are with the text input bar, portrait and landscape. The safe area layout guide will be very helpful. ;)

Reproducible in:

[x] This is reproducible in the sample project.
SlackTextViewController version: 1.9.5
iOS version(s): iOS 11.0
Device(s): iPhone X

Attachments:

[eliburke]

If you read through some of the other recent issues, there seems to be a general feeling that Slack is no longer maintaining this project.

Fortunately we have about 6-7 weeks until the general public will get their hands on the iPhone X.

Unfortunately, it looks like we're all going to have to solve this ourselves until someone steps up with a PR or a patch.

[hipwelljo]

@eliburke I hope that's not the case. In any case I stepped up with a PR. ;)