Fixing a bug/oversight. Having changed it because I noticed string.Join doesn't work with List and having a start and count parameter, I forget to change to call to string.Join itself.
* BrainFrontend.cs: Make the TimeLimit checking more appropriate,
  since we don't need the precision of the Stopwatch class.

* Chainey.cs: Make all sentence building print the time it took to
  build it.

* Database.cs: Give the methods more breathing room by increasing the
  default timeout of SQLite commands. There might be a threading bug,
  so also add diagnostics, most importantly the time it takes to
  execute all the inserts.
Some cosmetic changes in output.
Lay down the basics of an authentication system.
Add the ability to remove sentences from the underlying database, if
the user has the appropriate Authentication Level.
Update the interfaces for authentication.
Rename a file and bump version.
Bump version.