Additional round cleanup

neglected dep update from r87a6cad20c90: that rev also forces nightly rust due to https://github.com/rust-lang/rust/issues/23121

Send teams&flags on entering a room

Implement game start & engine messages

Implement game config messages

Enable all lints from the rust-2018-idioms suite. Additionally, fix the violation of the bare-trait-objects lint.

Just to be kind to vim which is failing at sniffing

implementation of team related messages

Store saved room in yaml

let's keep track of the racer room config

partial room implementation

rework of prior

handle edge polling properly

Merge default to ios-develop

Merge ios-develop into default

Added tag Hedgewars-iOS-2.1 for changeset 195208deff1d