v1.0.0b58

Fixed

• Register SanitizeRowsModifier as an IQueryModifier utility so
  that malformed Collection-query rows (missing or non-string i
  field) are dropped before plone.app.querystring.parseFormquery
  processes them. Upstream queryparser.py:73 otherwise sets
  query[None] = ... and the subsequent catalog(**parsedquery)
  in querybuilder._makequery fails at the Python level with
  TypeError: keywords must be strings — which the Collection edit
  widget cannot recover from. With the sanitizer in place the
  preview renders again, so editors can open their Collections and
  repair corrupted Subject / tag data through the UI.

  This is a defensive workaround for an upstream gotcha, not a fix for
  the underlying plone.app.querystring behavior. Closes #142.