Add a check for 2024 edition warnings so we make sure users can use Slint
in a crate using the 2024 edition when it gets released.
The warnings can be silenced as we don't handle types in Slint that
have Drop with side effects other than memory allocations
Updated the version from 1.1 to 1.2
Renamed the header to "Slint Royalty-free Desktop, Mobile, and Web Applications License"
Added definition of "Mobile Application" and grant of right
Moved "Limitations" to 3rd section and "License Conditions - Attributions" to 2nd section
Added flexibility to choose between showing "MadeWithSlint" as a dialog/splash screen or on a public webpage
Moved the para on copyright notices to section under "Limitations"
