small fixes

help cleanup and debug if operations fail
sync
fix some crashes in orc by not freeing orc stuff

a leak is better than a crash :( or build vips without orc if you don't
want a leak either

lots of stuff along the lines of:

==13114== Invalid write of size 8
==13114==    at 0xB81B229: orc_code_chunk_merge (orccodemem.c:107)
==13114==    by 0xB82B13D: orc_code_free (orccode.c:33)
==13114==    by 0xB81B89A: orc_program_free (orcprogram.c:175)
==13114==    by 0x6508AA4: vips_vector_free (vector.c:106)
add more orc debugging
option to trace all orc calls

used to generate the program here:

https://bugzilla.gnome.org/show_bug.cgi?id=731227
turn off orc program free

stops a crash, makes a memleak

see https://bugzilla.gnome.org/show_bug.cgi?id=731227
reenable orc program free

The bug has been fixed, see:

https://bugzilla.gnome.org/show_bug.cgi?id=731227

Summary:
	orc pre-0.4.19 leaks
	orc 0.4.19 crashes
	orc 0.4.20+ has few leaks and does not crash
update notes
TODO notes
bump image size limits for tiff

see https://github.com/jcupitt/libvips/issues/120#issuecomment-45324200
start hacking in better new from file
hackey hack
stage1 seems to work
finish reviding the fixed-up image load/save API
update notes
add vips_image_write_to_memory()
better shrink selection in vipsthumbnail

see:

https://github.com/jcupitt/libvips/issues/126

https://github.com/lovell/sharp/issues/41#issuecomment-44429413

thanks @ttback
punctuation
oops savers were not setting filename

when we added all the buffer loaders, we cul dno longer set filename in
VipsForeign, it's now the responsibility of each load class
Ooops