Fix handling of reserved characters

[alquerci]

Issue

Now reserved characters are removed that can provide key conflicts.

One case for example can be a key with a double foo@@bar should be differnent than foo@bar after normalization/clean.

Suggestion

Provide a character mapping like as

[
    // Firstly double all underscore.                                                                                                                                                                               
    '_' => '__', // Be able to retrieve the original key.

    // PSR-6 and PSR-16 reserved characters.
    '{' => '_1',
    '}' => '_2',
    '(' => '_3',
    ')' => '_4',
    '/' => '_5',
    '\\' => '_6',
    '@' => '_7',
    ':' => '_8',
]