Filter ElementHexa::decode() of non-hex chars

[GreyWyvern]

Type of pull request

• Bug fix (involves code and configuration changes)

About

Add a preg_replace() to ElementHexa::decode() so incoming strings are filtered of all non hexadecimal characters. Resolves #683.

Also remove check for the BOM (feff) if it exists. The existing function does a check for characters '00' at the beginning of the string to decide whether to 4-byte or 2-byte decode this string. It does not account for the 4-byte BOM and decodes such a string in a 2-byte fashion. It depends on further functions (in this case Parser::parseHeaderElement()) to repair the incorrectly decoded contents. Removing Checking for the BOM allows ElementHexa::decode() to return the correctly decoded contents the first time.

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[k00ni]

Thank you @GreyWyvern, looks good to me. Just a small remark.