- some were incorrect, now corrected
- some spinboxes were missing, now added (same as slider)
- still not all widgets have tooltips (notably blocksize + overlap)
* loaded and saved `samplebrain.ui` in Qt6 Designer
* generate `ui_samplebrain.h` on the fly (via `FORMS +=`)
* remove example files `sample.ui` and `ui_sample.h`
* remove `setMargin()` calls, these methods have been removed
* use `QFont::Bold` for `setWeight()` calls, numeric values aren't accepted anymore
* qualify `spiralcore::sample` in `block.cpp`'s `normalise()`
