Interface suggestions

First of all, thank you for an awesome app! We migrated away from Slack and have never looked back :)

I've got a few suggestions I hope you'll like. As it is, I feel the design is a bit cluttered and that the different sections purpose are a bit unclear.

### Home view/general

- The settings view slides in from the right but the button is left aligned. Either slide from left or move the button next to the search button. Also that would make room for another button at the left, if needed
- The "plus"-button feels very non-iOSy and it makes it hard to scroll horizontally in the last section on Home view. [Here](https://d26dzxoao6i3hh.cloudfront.net/items/2W1C2y3b161l062A172z/riot-plus-button.2G0G3M0W3Q36.png) is an alternative, courtesy of @yusf!

### People view
- I feel the "local contacts" section is redundant and confusing. I'm scrolling a list of my current 1:1 chats and then there's a list of my contacts? Also for a new user they could easily be confused with people online so you click a person to start chatting and then you've invited them. The solution is to remove it completely from People view, since it's present when selecting "Start chat"

### Room view
- The "room directory" feels out of place in the same way as "local contacts". I'd prefer to remove it and change the "Join room" option from the plus-button to look like "Start chat" and move the directory there. That would make it possible to either browse/search room or type in a link to join directly. Like on the web!

Start by locating the iOS Home, People, and Room views and reviewing their current navigation controls. Compare the requested settings, local contacts, room directory, and Join room changes with the existing web behavior referenced in the issue. Done would require an agreed scope and acceptance criteria for these several UI changes.

Written by the indexing model from the issue text.