Remove single alias/implication requests.

* Remove the single alias and implication request forms. From now
  on, bulk update requests are the only way to request aliases or
  implications.

* Remove the forum topic ID field from the bulk update request form.
  Instead, to attach a BUR to an existing topic you go to the topic then
  you click "Request alias/implication" at the top of the page.

* Update the bulk update request form to give better examples for the
  script format and to explain the difference between aliases and
  implications.

app/controllers/bulk_update_requests_controller.rb

@@ -5,7 +5,7 @@ class BulkUpdateRequestsController < ApplicationController
   before_action :load_bulk_update_request, :except => [:new, :create, :index]
 
   def new
-    @bulk_update_request = BulkUpdateRequest.new
+    @bulk_update_request = BulkUpdateRequest.new(bur_params(:create))
     respond_with(@bulk_update_request)
   end
 
@@ -57,6 +57,6 @@ class BulkUpdateRequestsController < ApplicationController
     permitted_params += %i[title reason forum_topic_id] if context == :create
     permitted_params += %i[forum_topic_id forum_post_id] if context == :update && CurrentUser.is_admin?
 
-    params.require(:bulk_update_request).permit(permitted_params)
+    params.fetch(:bulk_update_request, {}).permit(permitted_params)
   end
 end

app/controllers/tag_alias_requests_controller.rb

@@ -1,23 +0,0 @@
-class TagAliasRequestsController < ApplicationController
-  before_action :member_only
-
-  def new
-  end
-
-  def create
-    @tag_alias_request = TagAliasRequest.new(tar_params)
-    @tag_alias_request.create
-
-    if @tag_alias_request.invalid?
-      render :action => "new"
-    else
-      redirect_to forum_topic_path(@tag_alias_request.forum_topic)
-    end
-  end
-
-private
-  
-  def tar_params
-    params.require(:tag_alias_request).permit(:antecedent_name, :consequent_name, :reason, :skip_secondary_validations)
-  end
-end

app/controllers/tag_implication_requests_controller.rb

@@ -1,23 +0,0 @@
-class TagImplicationRequestsController < ApplicationController
-  before_action :member_only
-
-  def new
-  end
-
-  def create
-    @tag_implication_request = TagImplicationRequest.new(tir_params)
-    @tag_implication_request.create
-
-    if @tag_implication_request.invalid?
-      render :action => "new"
-    else
-      redirect_to forum_topic_path(@tag_implication_request.forum_topic)
-    end
-  end
-
-private
-
-  def tir_params
-    params.require(:tag_implication_request).permit(:antecedent_name, :consequent_name, :reason, :skip_secondary_validations)
-  end
-end