[feature] YAML/Python format \u0000 and \U00000000

[trr]

For convenience may I suggest adding the yaml formats:

Unicode codepoints up to 0xffff: "\uXXXX" (lowercase u, 4 uppercase hex digits)
Unicode codepoints above 0xffff: "\UXXXXXXXX" (uppercase U, 8 uppercase hex digits)

And for completeness I guess, "\xXX" can be used for 8-bit codepoints, or just 0 - 0x7f

This tool is very useful thank you.