we need to switch to autocommit mode before executing vacuums &
certain pragmas
also removed the pysqlite version workaround; we just use the
python-provided versions in all cases now as it is new enough
- tweak sync code so that a failure in loading the collection
won't leave the app with an unopen collection
- don't show corrupt collection message when the error is not
a db error
- catch the temp folder issue when loading the collection. i suspect
this was the issue that was causing some people to end up with
an open anki instance with no collection loaded
