3.0 release with some minor breaking changes

[simonw]

While working on search (#192) I've spotted a few small changes I would like to make that would break backwards compatibility in minor ways, hence requiring a 3.x release.

db[table].search() - I would like this to default to sorting by rank

Also I'd like to free up the -c and -f options for other purposes from the standard output formats here:

sqlite-utils/sqlite_utils/cli.py

Lines 48 to 58 in 43eae8b

	click.option("-c", "--csv", is_flag=True, help="Output CSV"),
	click.option("--no-headers", is_flag=True, help="Omit CSV headers"),
	click.option("-t", "--table", is_flag=True, help="Output as a table"),
	click.option(
	"-f",
	"--fmt",
	help="Table format - one of {}".format(
	", ".join(tabulate.tabulate_formats)
	),
	default="simple",
	),

I'd like -f to be used to indicate a full-text search column during an insert and -c to indicate a column (so you can specify which columns you want to output).

[simonw]

The breaking changes will be:

• table.search() now returns a generator that produces dictionaries, similar to table.rows_where()
• The -c shortcut no longer works, use --csv instead.
• The -f shortcut no longer works, use --fmt instead.

[simonw]

I'm going to release this as an alpha first and sit on it for a few days, since I don't want to ship any mistakes that would result in having to bump straight to 4.0!

[simonw]

Here's the alpha release: https://github.com/simonw/sqlite-utils/releases/tag/3.0a0