Cleanup and review for JENA-627.

.buildFilter:
   Remove unnecessary use of .remove
.insertAnyFilter:
   Comment that it modifies the content of the Expr list passed in.
   All callers take an outer copy before use of insertAnyFilter in a loop.
  

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1562754 13f79535-47bb-0310-9956-ffa450edef68