v2 breaking changes

[ueman]

This is a list of potential breaking changes.
Not all of them are already set in stone and i appreciate feedback on them.

Visual or behavioral changes

• Feedback mode is highlighted
• Change default feedback mode to draw (relates to UX is confusing. What does 'Navigate' do? Users don't know they can draw.  #69)

Code changes

• make screenshot image non nullable
• change BetterFeedback.of(ctx)?.show(...) to BetterFeedback.of(ctx).show(...)