Work around a SQLITE bug that resets the database busy timeout after a
successful query. Now we set the timeout after each database operation.
The timeout can now also be set via the R_LITEQ_BUSY_TIMEOUT
environment variable, and it defaults to 10 seconds, instead of 1 second.
consume() now has a poll_interval argument to set how often to poll
the queue for new jobs.
New is_empty() and message_count() functions (#18, @wlandau).
Get rid of annoying warning about closing unused connections (#15, #20, @wlandau).
LITEQ_CACHE_DIR environment variable to change the
default cache directory.First public release.