Fixes small Syntax error

Added internal support for an auto-expanding buffered reader, allowin…

…g for truly infinite lookahead. Changed lexer.New() to default to auto-expanding. Added contructor NewSize(), which replaces previous New(), accepting a readerBufLen parameter. Also added additional constructors NewFromString() and NewFromBytes() which allow you to deal with fixed-length input. Added Match*Func() functions which take a call-back function to validate the runes. Added MatchMinxMax*() functions to allow control over the number of runes that match. Modified word_count example to use NewSize(), and to deal with words longer than readBufferLen. Moved internal function runesContainRune() into external function go_pkg/runes.IndexRune()