new vips with faster google maps pyramid build

[jcupitt at gmail.com]

Hi all, I'm the vips maintainer.

There's a new stable version of vips, 7.34, with (thanks to Kacey)
much faster google maps centred pyramid build.

Google maps format lets you optionally centre images within tiles.
This used to be about half the speed of a plain pyramid build. On a
few systems (an 8-core AMD processor, for example) the slowdown was
almost a factor of 10. In 7.34, centre mode is only very slightly
slower than regular on all machines.

Source plus binaries for windows here:

  http://www.vips.ecs.soton.ac.uk/supported/7.34

The windows binary includes openslide. For mac, install with homebrew.

John