Better defaults in the UI

[Sawood Alam]

For better user experience you might want to:

• make the first three checkboxes checked by default
• add a link to the page where Perma.cc API key can be generated, and
• make the API key persist in user's browser's localstorage (if entered)

[Sawood Alam]

It looks like you have already fixed the first two after my email last night, so I checked them off.

[Sawood Alam]

Use https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage for the reference.

[Mohamed Aturban]

Yes, I already considered all of the three points you mentioned. Thanks.