Neoscore

- Make `neoscore.setup()` warn and skip if it detects it has been called more than once.
- Add `neoscore.render_to_notebook()` for conveniently emitting rendered images to Jupyter Notebook and compatible environments. Thanks demithetechie for helping with this!

- Update dependencies
- Pin pyqt5-qt5 to 5.15.2 to fix build failures on non-Mac systems. It seems that recent releases of this package do not support all systems.

- Fix bug with transform origin on `Text` objects with non-default text alignment.

- Fix `breakable_length` on all built-in spanners. Users with custom spanners should see [the updated documentation](https://neoscore.org/api/neoscore.core.spanner.html) on proper superclass declaration order.
- Make `PaintedObject.parent` no longer a kwarg providing a default `= None`. This aligns the class with how we do this everywhere else. This is technically a breaking change, but it's largely an internal class so we don't expect any users will be affected.

- Add support for 8va treble clefs ('treble_8va') and bridge clefs ('bridge'). Bridge clef acts like percussion clefs - it uses the center staff position as middle C regardless of staff line count.
- Add support for image transparency with new `opacity` field. The field is accessible through the `Image` constructor and a new `opacity` property.
- Add built-in tremolo support with new `Tremolo` class (by craigvear)
- Replace `Chordrest.notehead_column_width` with more general `Chordrest.notehead_column_bounding_rect`. This new method corrects some bugs with the implementation of the old method.

- Fix bug where viewport scales were set and got incorrectly (89)
- Fix viewport scaling support in Python < 3.8
- Slightly improve initial scene render performance by not clearing the scene before rendering.
- Support optimizing refresh functions when the scene doesn't change in every frame. This is done with a new class `neoscore.RefreshFuncResut`, which provided refresh functions can return. The class has a field, `scene_render_needed: bool = True` which tells neoscore whether it needs to clear and re-render the scene after the refresh function returns. This can be set to `False` in situations where the scene did not change in the frame, a significant optimization in complex scenes. It should be noted though that in complex scenes this could result in a noticeable frame rate drop when the scene _does_ change. The `input_scene_interaction` example has been updated to demonstrate this capability.
- Fix bounding rects on qt paths not starting at local origin, causing clipping errors on many objects, especially text objects.