world creation and generators menus moved to xml

res/layouts/pages/new_world.xml.lua

@@ -0,0 +1,35 @@
+settings = session.get_entry('new_world')
+
+function world_name_validator(name)
+    return name:match("^[%w-\\.\\ ]+$") ~= nil and not world.exists(name)
+end
+
+function settings.generator_name(id)
+    local prefix, name = parse_path(id)
+    if prefix == "core" then
+        return gui.str(name, "world.generators")
+    else
+        return id
+    end
+end
+
+function create_world()
+    if not document.name_box.valid then
+        return
+    end
+    local name = document.name_box.text
+    local seed = document.seed_box.text
+    core.new_world(name, seed, settings.generator)
+end
+
+function on_open()
+    if settings.generator == nil then
+        settings.generator = core.get_default_generator()
+    end
+    document.generator_btn.text = string.format(
+        "%s: %s", 
+        gui.str("World generator", "world"), 
+        settings.generator_name(settings.generator)
+    )
+    document.seed_box.placeholder = tostring(math.random()):sub(3)
+end