move raw converter setup to preferences

[zarl]

Tested on
OS X El Capitan Version 10.11.6 (Build 15G1108)
Hugin 2019.0.0.6a79af4e19b6 built by Niklas Mischkulnig

I didn't try dcraw yet but with both RawTherapee and darktable a first problem for users is the location of the respective cli. On macos it is inside the .app package, e.g. not directly available from the "select the cli" button/dialog of the raw import dialog.

My workaround is to find my copy of RawTherapee, right click to show contents, and in RawTherapee.app/Contents/MacOS/ opt+cmd+drag an alias of rawtherapee-cli to a place that's easy to find later (some place like the desktop or hugin's application folder). Same process for darktable.

When something goes wrong with my first raw import (hugin crashes) the whole setup is lost.

-> The setup for the path to the external raw converter should be moved to preferences

-> Is there a way to get access to the cli inside the .app "folder" from a standard file dialog in macos? If not we need to show a feasible workaround like the one describe above.

[tmodes (tmodes)]

I moved the settings to the preferences.
And for MacOS I added a default settings which pick up the default path /Applications/darktable.app/Contents/MacOS/darktable-cli or /Applications/RawTherapee.app/Contents/MacOS/rawtherapee-cli.