SharedStrings doesn't include/process the XML tags <b/> <I/> <u/> and <strike/> contained in rich text elements <rPr>.

[mikado2005]

Version

CoreXLSX (0.14.1) -- I'm using this one just because there's a CocoaPod for it.

Description of the bug

Cells in Excel which contain mixtures of font styles -- like italics and bold -- produce sharedStrings XML that include tags to mark the styles. For example, the word Italic within a cell:

        <r>
            <rPr>
                <i/>
                <sz val="12"/>
                <color theme="1"/>
                <rFont val="Calibri"/>
                <family val="2"/>
                <scheme val="minor"/>
            </rPr>
            <t>Italic</t>
        </r>

But CoreXLSX does not parse those formatting tags. This makes it impossible for Swift code to differentiate one font style from another within a cell.

Steps to reproduce

1. Make an Excel file with one cell filled in with a text like "Bold and Italic."
2. Load shared strings let sharedStrings = try file.parseSharedStrings()

There are no fields defined which handle the those XML tags .

[mikado2005]

Likewise, Font doesn't include underline.