v2: Indexing update

Features added in this release:

1. Adds an index
2. Ranks with tf-idf
3. By default shows 10 results (option to show all)
4. Ability to specify index by name (so you can create a particular named scope of flies and search only there)
5. Index location configurable
6. Excluded words option which ignores path if it contains them
7. Extracts text from pdfs, epubs, html, mhtml
8. Full stem reverse index

v1.0.2: Minor improvements

Changelog:

• Now using .net Tasks instead of Threads (apparently better performance. And there is a nice Task.WaitAll(Task[]) method that will wait on all tasks in an array to finish.
• Using BlockingCollection instead of a ConcurrentQueue. Only recently found out about this and it's a very powerful tool for the producer consumer pattern.
• BlockingCollection means the previous timing solution can be replaced totally (I was polling a "threadsRunning" flag and a checking if the Queue is empty).
• 100% test coverage (with a perf test).

v1.0.0: First release

'System.IO.Path.GetDirectoryName(Assembly.GetEntryAssembly().Location…