Cleanup exception handling after implementing multiple directory retries
Throw a RuntimeException if we fail to retrieve the path after MAX_TRIES (10),
  first using directory caches, then falling back to authorities.
Propagate the exception all the way to Consensus()
Propagate exceptions from Consensus to OnionRouter
Fix poor autogenerated code which hid the class generic T by naming the function generic T as well. Renamed function generic to U. (Credit to jlint)
Tidy unused imports, variables, and various other kinds of redundant code.
Fix documentation (somewhat). (Credit to jlint)
Merge pull request #4 from twilsonb/minor-fixes

Cleanup exception handling after implementing multiple directory retries