Update to angular 7

Also update flex-layout/material/cdk.

Angular 7 uses rxjs 6 which has a slightly different syntax.

It also uses Typescript 3.1

changed the description

@lmas60 please have a look at the changes since rxjs 6 uses a slightly different syntax.

Upgrade process is complete - you can merge when you want.

merged

mentioned in commit 4bbe5281