usermanual: fix for #9978
Make introspection work for zonesystem

... by skipping array size declarations and just letting the compiler
calculate the values for us using sizeof magic.
Deflicker: mode switching: gui complete
DEFLICKER_MODE_SOURCEFILE is working?
Deflicker "Automatic" is working?
IOP Exposure: histogram - when mode is automatic, change target level
Make sure deflicker will work only for raws (at least for now)
Some fixes for issues from hanatos review
Refactor histogram-related things a bit
Note that commit_params_late is less safe than commit_params
Rework lock release
Merge pull request #536 from LebedevRI/iop-exposure-deflicker-update

IOP Exposure - deflicker update
Do not rotate data upon loading. We will rotate it later in flip IOP
Refactor bitwise orientation into enum dt_image_orientation_t
IOP Flip: take care of flipping