add im_init_world() entry point

C++ programs need this as a function rather than just a macro, see
VImage.h

thanks Phil for finding this
Merge remote-tracking branch 'origin/7.36'

Conflicts:
	ChangeLog
	configure.ac
merge oops
Merge remote-tracking branch 'origin/master'
add --vips-profile

only added a few gates so far, try a visualiser next
parse profile output
stuff
better cache sizing in unbuffered sequential mode

Previously we only ever had a single tile of cache in unbuffered mode.
This could break with many threads, if thread requests crossed tile
boundaries.

Now have one tile per thread, plus a bit for slop.
Merge remote-tracking branch 'origin/7.36'

Conflicts:
	ChangeLog
	configure.ac
Merge branch 'master' into gate
Merge remote-tracking branch 'origin/gate' into gate
allow larger tile_size in dzsave

bump the tile_size limit up, thanks Petter Ranefall
Merge branch '7.36'
Merge branch 'master' into gate
cleanups, vipsprofile.py now works
fix typo in find_mosaic.c

thanks dcb314

https://github.com/jcupitt/libvips/issues/81
start adding cairo output
fix some clang warnings
add SEQ operation hint to conv

conv operations can run sequentially over images
add clang notes