Changes since 8.10.0:
- fix markdown -> xml conversion in doc generation
- remove typedef redefinitions to please old gccs
- fix regression in tiff pyramid thumbnailing [tand826]
- stop 0-length buffer being passed to imagemagick [lovell]
- convert no-profile CMYK to RGB on save [augustocdias]
- ensure SVG loader skips input with chars outside x09-x7F range [lovell]
- better mask sizing in gaussmat [johntrunc]
- fix tiffsave "squash" handling [barryspearce]
- fix jpegload autorotate [chregu]
- only start the background render thread on first use