1.0a10

The only changes in this alpha correspond to the way Datasette handles database transactions. (#2277)

• The database.execute_write_fn() method has a new transaction=True parameter. This defaults to True which means all functions executed using this method are now automatically wrapped in a transaction - previously the functions needed to roll transaction handling on their own, and many did not.
• Pass transaction=False to execute_write_fn() if you want to manually handle transactions in your function.
• Several internal Datasette features, including parts of the JSON write API, had been failing to wrap their operations in a transaction. This has been fixed by the new transaction=True default.