[raster] Refactor ST_AddBand to add multiple new bands in one call

[dustymugs]

Currently, the basic ST_AddBand() looks like...

ST_AddBand(
	rast raster,
	index int,
	pixeltype text,
	initialvalue float8 DEFAULT 0.,
	nodataval float8 DEFAULT NULL

) -> raster

But the problem is that to add multiple new bands, you have to call ST_AddBand many times. And if the raster has huge dimensions (e.g. 1000 x 1000) or many bands, the deserializing and serializing of the raster takes longer and longer as you add more bands.

Instead, ST_AddBand should have the ability to add multiple new bands at once. This will require a new data type...

CREATE TYPE addbandarg AS (
	index int,
	pixeltype text,
	initialvalue float8,
	nodataval float8
);

And a new "main" function...

ST_AddBand(
	rast raster,
	addbandargset addbandarg[]
) -> raster

The original "main" ST_AddBand() function (first code above) will now call the new "main" function.

Usage example:

SELECT
	St_Value(rast, 1, 3, 3),
	St_Value(rast, 2, 3, 3)
FROM (
	SELECT
		ST_AddBand(
			ST_MakeEmptyRaster(10, 10, 10, 10, 2, 2, 0, 0, 0),
			ARRAY[
				ROW(1, '64BF', 1234.567, NULL),
				ROW(2, '8BUI', 255, NULL)
			]::addbandarg[]
		) AS rast
) foo;

[dustymugs]

Added in r10130

[pracine]

Regina will be soooo happy!