bad settings that will cause content not to be indexed

#1018764, #1040002 by jhodgdon: Catch extra headers and active trail problems during search results display generation. Also fix one PHP warning.

#976272, #738382 by jhodgdon: Add minimum/maximum time constraints to search index cycling, on a per-module, per-environment basis. Make Search by Page Nodes reindex nodes when comments are added, deleted, or edited.

#806048 by jhodgdon: Make Search by Page use different cron index limit from core Search module, and make it so the core Search module can be set to 0 index limit.

#738382 by jhodgdon: Make SBP Users module reindex changed users with priority over the normal cycling through reindexing. Also prepare for 7.x release!

#952076 by jhodgdon: Add details section to status listing on search settings page, as an aid to figuring out what is not yet indexed. Also fixed up README file.

#738382 by jhodgdon: Make SBP Attachments and Nodes modules reindex changed nodes with priority over the normal cycling through reindexing.

#952076 by jhodgdon, bibo: Fix bug where unreadable items made the search index get stuck and blocked other items from indexing, especially file attachments. Also added some new tests for this.

#882328 by jhodgdon: Make excerpts with stemmed and exact matches show the earliest match even if there is an exact match later in the content.

#806030, #812406 by jhodgdon: Add theme support for search form to detect block vs. page. Add new setting to exclude HTML tag contents from search.

#816770 by jhodgdon: Add node variable to search result template for more flexible theming in Search by Page Attachments.

#674070 and #806028 by jhodgdon: Fix breadcrumb on search results page, and fix SBP module and tests so they work with new Drupal 7 version (see #553306).

#716342 by jhodgdon: Add random end to generated user names to avoid conflicts. Also, don't use $user as a local variable name.

#605458, #674070 by jhodgdon: Change the way role assignment is done during search indexing. Also increased efficiency in user queries and made sure only unblocked users are shown in search results. And cleaned up/documented a couple of coder warnings. And fixed some upgrade functions.