/blog/{year:\d{4}} notation doesn't support regex with curly brace hex escape

[nwellnhof]

The regex for the /blog/{year:\d{4}} notation should also allow A-Fa-f in inner curly braces to support hex escapes like {char:[\x{100}-\x{10FFFF}]}.

[nwellnhof]

Thinking more about it, constructs like \p{Uppercase=False} should also be supported. Maybe the pattern in Route.pm

\{((?:\{[0-9,]+\}|[^{}]+)+)\}

should be changed to

\{((?:\{[^{}]*\}|[^{}]+)+)\}