The length is an important property of a string and should be available
as a getter. The new size() method is consistent with std::string.
ChangeLog: [C++] Added `SharedString::size()`
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"
One key difference to the Rust way is what `slint::Window` means. In
Rust that holds the `WindowInner` and `slint::Window` is only exposed as
`&slint::Window`. This is possible because the component owns the
`Rc<dyn PlatformWindow>`, which has a function to return the
`&slint::Window`.
In C++ `slint::Window` is also exposed as `slint::Window&` in the
`window()` getter, but there's no way to get a reference to a C++
wrapper for the Rust `&slint::Window` that the `PlatformWindow` trait
returns. Therefore in C++ `slint::Window` wraps `Rc<dyn
PlatformWindow>`.
