Add implicit this to locals variables of partial

When using `Cuba::Mote` and doing `partial`, we've changed
it so that you always have to use the explicit context `this`:

`{{ this.partial("something") }}`

In addition, the partials automatically get `this` as
a local variable.

Helpers and all other stuff are accessed through this too.

lib/cuba/contrib/mote.rb

@@ -11,7 +11,7 @@ def self.setup(app)
     end
 
     def partial(template, locals = {})
-      mote(mote_path(template), locals)
+      mote(mote_path(template), locals.merge(this: self))
     end
 
     def view(template, locals = {}, layout = settings[:mote][:layout])
@@ -31,7 +31,7 @@ def mote_path(template)
     end
 
     def mote_vars(content)
-      { context: self, content: content }
+      { content: content }
     end
 
     class NoLayout < StandardError

test/mote.rb

@@ -29,6 +29,10 @@
     render("home", title: "Hola")
   end
 
+  on "partial-fu" do
+    res.write partial("partial1")
+  end
+
   on "abs_path" do
     res.write view("./test/views/custom/abs_path.mote", title: "Absolute")
   end
@@ -46,6 +50,15 @@
   assert_response body, ["<title>Hola</title>\n<h1>Home</h1>\n\n"]
 end
 
+test "partial-fu" do
+  # We verify that nesting partials and contexts are passed along properly.
+  _, _, body = Cuba.call({ "PATH_INFO" => "/partial-fu/A", "SCRIPT_NAME" => "" })
+  assert_response body, ["partial1\npartial2\n/partial-fu/A\n\n"]
+
+  # And that we're able to use req.path in the inner partials without an issue.
+  _, _, body = Cuba.call({ "PATH_INFO" => "/partial-fu/B", "SCRIPT_NAME" => "" })
+  assert_response body, ["partial1\npartial2\n/partial-fu/B\n\n"]
+end
 
 test "partial" do
   _, _, body = Cuba.call({ "PATH_INFO" => "/frag", "SCRIPT_NAME" => "" })

test/views/partial1.mote

@@ -0,0 +1,2 @@
+partial1
+{{ this.partial "partial2" }}

test/views/partial2.mote

@@ -0,0 +1,2 @@
+partial2
+{{ this.req.path }}