Keep using kilt for rendering

Directly using Crystal's ECR seems to be causing issues, so
don't use kemal's 'render' macro and patch 'content_for' to
have the same behavior as before Kemal v1.1.1

src/ext/kemal_content_for.cr

@@ -0,0 +1,16 @@
+# Overrides for Kemal's `content_for` macro in order to keep using
+# kilt as it was before Kemal v1.1.1 (Kemal PR #618).
+
+require "kemal"
+require "kilt"
+
+macro content_for(key, file = __FILE__)
+  %proc = ->() {
+    __kilt_io__ = IO::Memory.new
+    {{ yield }}
+    __kilt_io__.to_s
+  }
+
+  CONTENT_FOR_BLOCKS[{{key}}] = Tuple.new {{file}}, %proc
+  nil
+end

src/invidious.cr

@@ -16,7 +16,12 @@
 
 require "digest/md5"
 require "file_utils"
+
+# Require kemal, kilt, then our own overrides
 require "kemal"
+require "kilt"
+require "./ext/kemal_content_for.cr"
+
 require "athena-negotiation"
 require "openssl/hmac"
 require "option_parser"

src/invidious/helpers/macros.cr

@@ -48,13 +48,19 @@ module JSON::Serializable
   end
 end
 
-macro templated(filename, template = "template", navbar_search = true)
+macro templated(_filename, template = "template", navbar_search = true)
   navbar_search = {{navbar_search}}
-  render "src/invidious/views/#{{{filename}}}.ecr", "src/invidious/views/#{{{template}}}.ecr"
+
+  {{ filename = "src/invidious/views/" + _filename + ".ecr" }}
+  {{ layout = "src/invidious/views/" + template + ".ecr" }}
+
+  __content_filename__ = {{filename}}
+  content = Kilt.render({{filename}})
+  Kilt.render({{layout}})
 end
 
 macro rendered(filename)
-  render "src/invidious/views/#{{{filename}}}.ecr"
+  Kilt.render("src/invidious/views/#{{{filename}}}.ecr")
 end
 
 # Similar to Kemals halt method but works in a