Make the scope of many local variables smaller.

spec/tiny_spec.lua

@@ -1,3 +1,8 @@
+local GLOBALS = {}
+for k, v in pairs(_G) do
+    GLOBALS[k] = v
+end
+
 local tiny = require "tiny"
 
 local function deep_copy(x)
@@ -230,4 +235,8 @@ describe('tiny-ecs:', function()
 
     end)
 
+    it("Doesn't pollute the global namespace", function()
+        assert.are.same(_G, GLOBALS)
+    end)
+
 end)