Add superscript

[ashahabov]

Make possibility of adding superscript content.

Expected Behavior

There is a method on the TextBox, Paragraph or Portion level that allows adding superscripts. Adding superscript can be looked like this:

var pres = SCPresentation.Open("add-superscript.pptx", true);
var autoShape = pres.Slides[0].Shapes.GetByName<IAutoShape>("AutoShape 1");
var paragraph = autoShape.TextBox.Paragraphs[0];

var newPortion = new SCPortion();
newPortion.Font.OffsetEffect = 30;
newPortion.Text = "®";
paragraph.Portions.Add(newPortion);

Check List

• implement feature;
• add unit-test.

Pull Requests

• Add superscript/subscript #347
• Remove null check before setting run baseline #353

Testing

• ✔ IFont.OffsetEffect.get()
• ✔ IFont.OffsetEffect.set()

[ashahabov]

@amescodes, could you please check the following test case? Looks like setter of OffsetEffect breaks presentation:

branch: master (code was refactored)
presentation: autoshape-case010.pptx
validator log: ooxml-validator.2022-10-12T06_53_14.318Z.json.zip

Steps:

1. Run:

using var pres = SCPresentation.Open("autoshape-case010.pptx");
var font = pres.Slides[2].Shapes.GetById<IAutoShape>(2).TextFrame!.Paragraphs[0].Portions[0].Font;

font.OffsetEffect = 12;

pres.Save();

2. Open modified autoshape-case010.pptx

Actual behavior: PowerPoint suggests "Repair":

Expected behavior: PowerPoint should not suggests "Repair".