Merge pull request #727 from lakkatv/lakka

(Lakka) Fix a performance issue in lakka_frame when displaying a submenu
(Frontend) Push load game history when process_args returns 1 for
console/mobile
Menu context destroy needs to be grouped in HAVE_MENU ifdef
Correct 'ret' return of process_args at least - 0 is for content
being loaded, 1 is if content is not loaded
(Lakka) Code refactoring and performance improvements