Support asscii classes

[hedhyw]

[[:alnum:]]    alphanumeric (== [0-9A-Za-z])
[[:alpha:]]    alphabetic (== [A-Za-z])
[[:ascii:]]    ASCII (== [\x00-\x7F])
[[:blank:]]    blank (== [\t ])
[[:cntrl:]]    control (== [\x00-\x1F\x7F])
[[:digit:]]    digits (== [0-9])
[[:graph:]]    graphical (== [!-~] == [A-Za-z0-9!"#$%&'()*+,\-./:;<=>?@[\\\]^_`{|}~])
[[:lower:]]    lower case (== [a-z])
[[:print:]]    printable (== [ -~] == [ [:graph:]])
[[:punct:]]    punctuation (== [!-/:-@[-`{-~])
[[:space:]]    whitespace (== [\t\n\v\f\r ])
[[:upper:]]    upper case (== [A-Z])
[[:word:]]     word characters (== [0-9A-Za-z_])
[[:xdigit:]]   hex digit (== [0-9A-Fa-f])

They can be defined as [:lower:] in TokenClass.