Application will pick translation dictionaries based on the system default language

on first start of Slic3r.
Updated help menu (removed reference to the upstream manual)
Fixed some OpenGL assert due to glOrtho being called with zero Z span.

src/slic3r/GUI/GLCanvas3D.cpp

@@ -3612,7 +3612,8 @@ void GLCanvas3D::_resize(unsigned int w, unsigned int h)
         }
 
         // FIXME: calculate a tighter value for depth will improve z-fighting
-        float depth = 5.0f * (float)bbox.max_size();
+        // Set at least some minimum depth in case the bounding box is empty to avoid an OpenGL driver error.
+        float depth = std::max(1.f, 5.0f * (float)bbox.max_size());
         m_camera.apply_ortho_projection(-w2, w2, -h2, h2, -depth, depth);
 
         break;