Redesign the Welcome page, making it friendlier and better looking

The old Welcome page is looking a bit dated, and we can do better. This replaces it with a streamlined version with a "Compatible with Mastodon" badge.

This also adds a "Settings" button on the main page, so you can view the settings alongside network settings before continuing.

Other misc improvements:

• The settings is now accessible from application start-up, useful to get version information, configuring misc settings and you can configure network settings out of the box.
• The "Pick a Server" button is focused by default, improving keyboard navigation.

"Compatible with Mastodon"? -> this complies with the Trademark Policy.

Breeze Light

Before	After

Breeze Dark

Before	After

Mobile

Of course I didn't forget about mobile! It looks good here too:

Note that I still want to add some additional text to this page, such as a short rundown of what Mastodon is. That's easy to add later, though.