Add playing card example

[ednolan]

This example provides an example of the kind of transformation that can only be performed on UTF-32 code units and not UTF-8 code units. Changing the second most significant nibble of the underlying code point is intractable on UTF-8 code points but can easily be done with UTF-32.

[coveralls]

Pull Request Test Coverage Report for Build 11811017196

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 11508724943:	0.0%
Covered Lines:	468
Relevant Lines:	468

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💛 - Coveralls