Small improvements to Indexer class.

- Added some error checking (file not found, etc)
- Deprecated list-based index methods (use file glob or write your own)
Made IndexTool accept file globs in addition to whole dirs.
Added passing parameters to DocIndexer to IndexTool.
Added error message if main contents field cannot be detected.

This can happen if you try to open an empty index.
Updated supplied test data.

There's now some test data for each of the indexers provided.
Supplying a single file to IndexTool also works now.
Fixed bug in DocResults when you have no hits, only documents.