While it's nice to have a fixed chrome version it slows down the yarn install,
downloads a lot of things, and the chrome version depends on various
system packages so one needss to have chromium installed anyway.

This means developers that want to work on tests need firefox and chdomium installed.

Sadly I couldn't find a way to make browsers optional in case the developer
only has one installed.

Use tdd in all cases to be more consisstend.
Also since last year we can use chai with rollup directly, so
do that everywhere instead of relying on karma-chai injecting
it in to the global scope.

Using lerna with npm breaks various npm commands such as "outodated"
etc.

Switch yarn with namespaces. lerna is only used to run commands on all
packages and maybe publish them etc. yarn 2.x has extra workspace features
like running commands for all packages, so with 2.0 we might also get
rid of lerna.