Fixed the mismatch between Character#isWhitespace and [ \t]+

In HbsLexer.g4#consumeUntil Character.isWhitespace is used for recognizing token delimiter. Character.isWhitespace matches whitespace (\u0020) and tab (\u0009), as well as other characters. But HbsLexer regards only  \u0020 and \u0009 as SPACE.

    SPACE
     :
      [ \t]+
     ;

So, it causes SyntaxError if template contains \u000b (Vertical tab) or , \u3000 (IDEOGRAPHIC SPACE), and so on. 

I would appreciate if you could regard only ' ' and '\t'  as a delimiter instead of using Character.isWhitespace, in consumeUntil.