fixed broken regular expression in scheme lexer
fixed broken regular expression in scheme lexer

aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments,aswinpj/Pygments