Working on assistant's performance when it has to add a whole lot of files
(10k to 100k). 

Improved behavior in several ways, including fixing display
of the alert in the webapp when the default inotify limit of 8192
directories is exceeded.

Created a new TList data type, a transactional DList. Much nicer
implementation than the TChan based thing it was using to keep track of the
changes, although it only improved runtime and memory usage a little bit.
The way that this is internally storing a function in STM and modifying
that function to add items to the list is way cool.

Other tuning seems to have decreased the time it would take to import 100k
files from somewhere in the range of a full day (too long to wait to see),
to around 3.5 hours. I don't know if that's good, but it's certainly better.
