The database API for user variables has changed somewhat again, this
time closer to the proper vision. There are now two separate sled
Trees in the Variables struct, one for user-defined variables, and one
for counts. Keys have been changed to be username-first, then room ID.
The signatures of the functions now also use a strongly-typed struct,
UserAndRoom.
As part of this, the Context object now once again avoids allocating
new strings.
Other random changes included here:
- Remove tempfile crate in favor of sled temporary db config.
- Add bincode crate in anticipation of future (de)serializing.
projectmoon