POC: translation done by darktable.

[TurboGit]

This is a POC on how Lua script translation could be handled directly in darktable.

The darktable part

• Add lua-scripts has a submodule in src/external

• Add all lua files into po/POTFILES.in

This will make it possible with the current main darktable translation workflow to also translate the scripts.

The Lua script part

• As proposed in this PR remove the gettext domain, use a common one to share as much as possible the strings across darktable and all lua scripts.

• Use common casing for all Lua strings. Indeed there is some string identical except for the casing. Again this is to share a maximum of string.

• Remove any spaces in start or end of strings, the layout must not be done in strings. I see for example "of " and some other cases.

Redesign

• As discussed in issue #438 we also want to redesign the Lua script description to be more uniform and structured. Those description must be done using _('...") to allow for translation. Some description are quite big, I'm wondering if we want this in the dt tooltip or maybe a lite description in dt tooltip and a full description in main dt documentation. To be discussed.

• We probably want to have a string for the name of the module provided by the script. As I understand we use the script filename for the name today. This is not really user friendly, so better have a string for the name of the script which is displayed on the UI (as done for dt modules).

• The redesigned of the UI with standard button as already discussed.

@wpferguson : This is my current idea to make Lua scripts a first class citizen. Let me know how it sounds to you.

I hope I have not missed something, but at least with this POC I was able to translate Lua scripts in French.