Fix SongEditor Snap Size to Adjust with Time Signature

[regulus79]

Description

This PR changes the way the snap size in the Song Editor is set up to accommodate odd time signatures. Instead of being solely powers of two, the snap sizes < 1 bar are now also multiples of the current time signature.

The snap sizes in general look like:

• 2^3
• 2^2
• 2^1
• 1
• 1 / (numerator)
• 1 / (numerator * 2^1)
• 1 / (numerator * 2^2)
• 1 / (numerator * 2^3)

The snap sizes are recalculated and the ComboBox is repopulated whenever the time signature changes.

2024-12-13.13-10-14.mp4

Changes

• A new slot was added to SongEditor, updateSnapSizes(), which is connected to Song::timeSignatureChanged. This function recalculates the snap sizes given the current time signature numerator.
• A vector m_snapSizes was added to SongEditor so that the snap sizes do not have to be recalculated whenever they are requested.
• The arrays SNAP_SIZES and PROPORTIONAL_SNAP_SIZES were removed from SongEditor and replaced with the integers SNAP_SIZES_SMALL and SNAP_SIZES_LARGE, which determine the number of divisions greater than or less than 1 bar.