Changelog:

Adds:
- Elemental skills: you can unlock (on the skill menu) and use elemental skills
with elemental weapons of the same element. You need at least a skill level 3
(Alpha) or level 4 (Beta) to use an elemental skill.
- 12 new swords (elemental swords)
- You can recycle scepters with the crusher, result in gems and new materials
that will be used later
- UI is now compatible with multiple skins, you can create your own and add
it in assets/ui_skin/ using the base "skin_default" (don't forget to change
the file "skins.json" to add your new skin)
- New secret recipe

Fix:
- world generator bug: number of prisons can be low
- transformation problems with repty/eagle/devourer (missing flag)

PS: Multi elemental swords are planned