Add config option to autoboot into 3DS and DSi homebrew menu, without
going through Home Menu (nor launching it).
For 3DS homebrew, this requires homebrew built with libctru v2.0.0 or
later (v2.0.0 was released 2.5y ago).
We simulate a "reboot into title" to achieve this. This being said, when
launching stuff like Pokemon US/UM on O3DS, Home Menu reboots into
itself and not the game directly. This will cause Home Menu to crash if
you use this feature and configure it to use a non-default memory layout
(but if you don't, Home Menu will work just fine).
- Stop spamming mcu reads... use the GPIO pin to know if there's a MCU interrupt, instead
- Wait for the MCU interrupts to be raised when powering up LCD+backlights
- Also turn off LCD+backlight when needed
