If the effectively drop shadow size would be zero, the FemtoVG and Skia item renderers would panic. The following test-case reproduces this:
```slint
export component Test inherits Window {
Rectangle {
drop-shadow-color: black;
drop-shadow-offset-x: 1px;
drop-shadow-blur: -0.5px;
width: 0.5px;
height: 0.5px;
background: blue;
}
}
```
ChangeLog: [Renderers] Fix panic with FemtoVG and Skia renderers for certain drop shadows.
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"
Previously, all the closures passed to `get_or_update_cache_entry` would
have to make sure that the scale factor is an included dependency. This
is error prone, as the parent commits show.
Instead, this change adds a property tracker to each ItemCache and lets
the renderer clear the cache if the scale factor changes.
Strictly speaking this may delete too many entries from the cache (not
all depend on the scale factor), but on the other hand this doesn't
happen very often so we trade robustness over efficiency.
