Add "Call stack:" to the log when a module load fails

lib/msf/core/module_manager/loading.rb

@@ -109,4 +109,4 @@ module Msf::ModuleManager::Loading
 
     count_by_type
   end
-end
+end

lib/msf/core/modules/loader/base.rb

@@ -419,6 +419,7 @@ class Msf::Modules::Loader::Base
 	  log_lines << "#{module_path} failed to load due to the following error:"
 		log_lines << error.class.to_s
 		log_lines << error.to_s
+		log_lines << "Call stack:"
 		log_lines += error.backtrace
 
 		log_message = log_lines.join("\n")