Fix an issue with Solr. Sometimes, even if a dynamic field was not used by any documents, and even after optimizing the index, the dynamic fields were still in the index. So, we couldn't remove them. However, in some cases, it was causing issues down the road. So, this fix take care to check if each field returned by the Luke Solr service are actually used by at least one document. If they are, then we add it to fieldsIndex.srz, if they are not, then we simply ignore it, and it doesn't make it into the fieldsIndex.srz file.

We also fixed a few issues in CRUD: Create and CRUD: Update related to that. Sometimes, the $newFields variable was TRUE even if it shouldn't.