IndexTool can now read parameters from a .properties file.

Parameters from properties file are passed to DocIndexer class. Use the
--indexparam <file> option to indicate the .properties file.
Made indexers better customisable via parameters.

* Made sure indexer constructor has access to parameters
* Made sensitivity settings automatically customisable per property
* Included reasonable default sensitivity settings based on prop. name
Added error message if .properties file doesn't exist.
QueryTool: moved short utility functions to bottom of file.
Added wordlists functionality to QueryTool.

You can load a list of words from an external file and include a random
word from the list in your queries. This is useful in stress testing
scripts.