Metadata viewer: indicate that the focal length is given in milimeters
(cherry picked from commit 54d7e090ea4b9f9ab2441b601e21f2c6caf849d8)
Metadata viewer: don't display invalid/unusable "focus distance" values
(cherry picked from commit ca342a41978a24bffe8bb1b59ede2b2687143692)
cache: make stats work on legacy compiler + arch.
(cherry picked from commit d2c07e36e332af241dcfc5064091b0c584fb7970)
color picker: better account for invalid local color picker data in several places

if the local color picker is positioned outside the module's image area it can not
deliver valid data. take appropriate action in this case (depends on where we use
the color picker).
(cherry picked from commit 48bd6fd016604ae1d3db3b4d0378d582763a8cb1)

Conflicts:
	src/iop/levels.c