This removes a lot of allocations and speeds up the compiler step
a bit. Sadly, this patch is very invasive as it touches a lot of
files. That said, each individual hunk is pretty trivial.
For a non-trivial real-world example, the impact is significant,
we get rid of ~29% of all allocations and improve the runtime by
about 4.8% (measured until the viewer loop would start).
Before:
```
Benchmark 1: ./target/release/slint-viewer ../slint-perf/app.slint
Time (mean ± σ): 664.2 ms ± 6.7 ms [User: 589.2 ms, System: 74.0 ms]
Range (min … max): 659.0 ms … 682.4 ms 10 runs
allocations: 4886888
temporary allocations: 857508
```
After:
```
Benchmark 1: ./target/release/slint-viewer ../slint-perf/app.slint
Time (mean ± σ): 639.5 ms ± 17.8 ms [User: 556.9 ms, System: 76.2 ms]
Range (min … max): 621.4 ms … 666.5 ms 10 runs
allocations: 3544318
temporary allocations: 495685
```
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"
A None value means the file on disk is the golden version.
We have an editor, the LSP and the preview that all need to at least
notice when they have newer data then their peers. So IMHO it makes
sense to have an optional document version around.
The language server protocol makes use of a version number already. This
patch moves that code into the compiler so that it is stored with the
actual data getting versioned.
Note, this goes against the gettext documentation's recommendation:
https://www.gnu.org/software/gettext/manual/gettext.html#Contexts
> Finding a canonical msgctxt string that doesn’t change over time can be hard.
> But you shouldn’t use the file name or class name containing the pgettext
> call – because it is a common development task to rename a file or a class,
> and it shouldn’t cause translator work.
