Fix constant recomputation of preview pipe

This might be a little dirty by just decreasing the chance of the
race condition to hit us. Not sure if proper locking would work though,
see comment in commit.
Merge pull request #595 from MRIG/master

Updated Dutch translation
cameras.xml: remove extraneous hyphen
Merge pull request #596 from dtorop/cameras-hyphen

cameras.xml: remove extraneous hyphen
build: make it compile without gphoto2 again.
Fix GTK warnings when SVG files can't be loaded
lua : move view_changed event out of the GTK thread
lua : fix shortcuts not working
Update French translation.

For #9988.
lua : add a reset() function for libs
force self->widget to null when a lib's UI is destroyed
lua : add a way to easily know if a lib is displayed on the screeen
Fix infinite reprocess (FIXME: why g->reprocess_on_next_expose == TRUE ?)
IOP Exposure: Deflicker: show what exposure correction have actually been used
lua : fix tracebacks not working
adobe_coeff: Canon PowerShot G1 X Mark II support
adobe_coeff: SONY DSC-RX100M3 support
rawspeed: correct nikon d800 white point
usermanual: proofreading new stuff thanks to David Vincent-Jones
usermanual: update on the watermark module

and a few further fixes