Merge pull request #1111 from mprobinson/audio-latency

Avoid compiler warnings in null_write_handler()
Start reimplementing tween.c functions
Clean out a few leaks. Still leaks at lines 3758, 3759 and 3864, though, and those seem far nastier to fix...
Cut down on some calls made to add_tween
(settings_data) Fix the leaks at 3758 and 3759; better one leak than three.
(settings_data) Might as well mark the last one.
Reduce CPU features log spam
Merge pull request #1112 from mprobinson/log-spam

Reduce CPU features log spam
Initialize parport pin report buffer
Merge pull request #1113 from mprobinson/parport-bug

Initialize parport pin report buffer
(XMB) Cleanups
Add userdata variable to menu_handle_t
(GLUI) Implement menu->userdata for GLUI
(Lakka) Start moving global variables over to lakka_handle_t struct, and
bind it to driver.menu->userdata
(Lakka) Move categories over to userdata too
(Lakka) Create lakka_free_userdata
Move more variables to lakka_handle_t
Move margin variables over to lakka_handle_t
(Lakka) Move more variables over
(Lakka) Move more variables over pt. 2