start on inplace
fix stray uses of "layer" in openslideload documentation
drop error freeze/thaw around openslide_open()

openslide_open() hasn't been able to cause a call to vips_error() since
c98d6543.
update for new format support in OpenSlide 3.4.0
use openslide_detect_vendor() on OpenSlide 3.4.0

It is much more efficient than openslide_open().  It also fixes a bug:

If openslide_open() failed, we had no way of knowing whether it was an
interesting failure (for relevant slide formats) or an uninteresting
one (for a generic TIFF).  So, the is_a method would always return false
in this case.  This could cause unexpected results; for example, on MIRAX
slides, VIPS would open the .mrxs file itself (a JPEG thumbnail) and the
user would be left wondering where all their pixels went.  Now, if there
is an interesting failure, is_a will succeed but header/load will fail.
Merge pull request #100 from bgilbert/openslide-3.4

Updates for OpenSlide 3.4.0
add "rgbjpeg" flag to tiffsave

add a secret "rgbjpeg" flag to tiffsave to help IIPImage server

iipimage server 0.9.9 and earlier don't handle YCbCr-coded JPEG tiffs
correctly ... setting --rgbjpeg makes vips output RGB coded JPEG tiff
which iipsrv can handle.

Using this flag makes files 2x to 3x larger with no quality improvement,
so it is tagged as deprecated to keep it hidden.
fix a warning
Merge remote-tracking branch 'origin/7.38'
formatting
vips_sink_screen() now invalidates for you

clients no longer need to call vips_image_invalidate_all()
update valgrind supp
bg render thread quits on shutdown

fixes a small memleak
oop, invalidate mask as well
oops!
check for init before render shutdown

we could shut down render without having inited it, check

thanks andrea
small operation description fixes

more consistency, fix a couple of missing ones
add source_space to vips_colourspace()

you can now specify the source colourspace, if you want
sync
add VIPS_OPERATION_DEPRECATED

and fix a tiny problem in vipswrap7