projekt kivitendo

IMAPClient: FIX: gültige Zeichen für Zeichensatzname verwenden

https://www.rfc-editor.org/rfc/rfc2978#section-2.3
   mime-charset = 1*mime-charset-chars
   mime-charset-chars = ALPHA / DIGIT /
               "!" / "#" / "$" / "%" / "&" /
               "'" / "+" / "-" / "^" / "_" /
               "`" / "{" / "}" / "~" 
   ALPHA        = "A".."Z"    ; Case insensitive ASCII Letter
   DIGIT        = "0".."9"    ; Numeric digit