Merge pull request #728 from lakkatv/lakka

(Lakka) Code refactoring and performance improvements
Rewrite rarch_main_wrap - we need a way of getting a valid argc/argv
pair for consoles where we get stupid argc/argv pairs back that need
to be 'converted' into something that RetroArch's PC-style args parsing
can deal with
(Menu) Forgot to deinit if main_is_init is true
(Lakka) Store the content icons in the category to save ram