Patch: enable UDF "url_param" to handle tildes and underscores

[sakamossan]

We can use underscore and tilde in URL. I have made them capturable.

Characters that are allowed in a URI but do not have a reserved
purpose are called unreserved. These include uppercase and lowercase
letters, decimal digits, hyphen, period, underscore, and tilde.

• RFC 3986: Uniform Resource Identifier (URI): Generic Syntax

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[danieldeleo]

Thanks for adding this fix!