Remove a bunch of strlen()
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