fixed entity problem in exslt:tokenize uncovered by newapi.xsl changed to

* libexslt/strings.c: fixed entity problem in exslt:tokenize
  uncovered by newapi.xsl
* libxslt/transform.c,libxslt/pattern.c,libxslt/keys.c: changed
  to use IS_BLANK_CH for char compares (fixes warnings)