Fix #21110 - Wavy glissando text position

- Text over a glissando wavy line collided with line.
- The wavy line occasionally collided with final note and was not always centred within the two notes.

Fixed in Glissando::draw() by:

- linking text vert. offset to line type
- always rounding down the number of wavy elements and positioning the line according to the number of actual elements
fix #21127, fix #21123, fix layout of square bracket
Fix #21121 - Pasting unstyled text causes crash

Fixed in ChordRest::drop() by checking for proper text style.
fix #21120: Increasing rest value causes corruption
Merge pull request #365 from mgavioli/Fix_21110_Wavy_glissando

Fix #21110 - Wavy glissando text position
Merge pull request #366 from mgavioli/Fix_21121_Pasting_unstyled_text_crashes

Fix #21121 - Pasting unstyled text causes crash
fix #20964: 7 and 9 tuplet groups result in a corrupted score when reopened
fix #20964: take 2
fix #20964: take 3...
remove left over from previous commits