Rename and format ECR files

src/routes/main.cr

@@ -4,7 +4,7 @@ class MainRouter < Router
   def initialize
     get "/login" do |env|
       base_url = Config.current.base_url
-      render "src/views/login.ecr"
+      render "src/views/login.html.ecr"
     end
 
     get "/logout" do |env|

src/routes/opds.cr

@@ -4,13 +4,13 @@ class OPDSRouter < Router
   def initialize
     get "/opds" do |env|
       titles = @context.library.titles
-      render_xml "src/views/opds/index.ecr"
+      render_xml "src/views/opds/index.xml.ecr"
     end
 
     get "/opds/book/:title_id" do |env|
       begin
         title = @context.library.get_title(env.params.url["title_id"]).not_nil!
-        render_xml "src/views/opds/title.ecr"
+        render_xml "src/views/opds/title.xml.ecr"
       rescue e
         @context.error e
         env.response.status_code = 404

src/routes/reader.cr

@@ -56,7 +56,7 @@ class ReaderRouter < Router
           next_entry_url = "#{base_url}reader/#{title.id}/#{next_entry.id}"
         end
 
-        render "src/views/reader.ecr"
+        render "src/views/reader.html.ecr"
       rescue e
         @context.error e
         env.response.status_code = 404