Improve translations generation

[Pictor13]

Issue: custom translations are overridden when regenerating the config files from the resource skeleton.

We could:

• Separate translations in 2 different files (default and custom) so that regeneration just restores the defaults without affecting or removing the custom/added translations
• Support an automatic generation of the custom translations file, containing the preset list of needed translations, based on the list of attributes from the entity schema of the generated resource. This would speed-up the translation process, saving from having to figure out what keys have to be translated.
  • A similar strategy could be used also for the generated view_templates files.