start adding tiff load from buffer

see

https://github.com/jcupitt/libvips/issues/25
add load from buffer
fix for new ubuntu
use float div for sigma calc in gaussblur

thanks aferrero2707
add .vips as an alternative vips suffix

helps imagemagick, see

http://www.imagemagick.org/discourse-server/viewtopic.php?f=2&t=25445&p=110491#p110491
tiff load from buffer done
Merge remote-tracking branch 'origin/tiffload-buffer'

Conflicts:
	ChangeLog