Hardware code cleanup + new documentaion/findings.

Added proper GPIO driver.

Don't disable vfp (no harm in leaving it on). Lots of small, mostly style changes.

A few MMU code fixes.

Added GPU reset code (unused because it works as is). Disabled tag RAM and L1 parity checking on ARM11. Don't rely on code overhead at SD card init for the 74 clock pulses. Implemented new cycle accurate delay function.

More code improvements/documentation.

A few code optimizations.

Simplified MMU mappings a bit and added documentation which bits are which.

Updated SPI code. Added unused SPICARD code.

Fix for the HOME button workaround, other bugfixes and cleanup.

HID refactor.

Simplify CODEC code even more.

[spiflash.c] Set offset directly instead of byte writes.

Minor fixes/adjustments to SPI code. Moved spiflash code to ARM11.

Added SPI and CODEC drivers. Unused right now.

[ARM11] Disable FIQs properly.

Change power LED pattern to indicate sleep when the lid is closed.

Re-enable code to set MCU IRQ bitmask.

[ARM11] Prevent possible UB with the MMU and enable icache a bit earlier.

Added SHA + NDMA prototype + some notes.

Introducing iomemcpy() and iomemset().

Added interrupt safe I2C reg write. Fixed poweroff on exceptions.

[ARM11] Allow setting IRQ handlers to NULL like on ARM9 + cleanup.

General cleanup + possible I2C bugfix.

Move more I2C stuff to mcu.c/h.

Use I2C IRQs. I2C code cleanup + other changes required after the former.

Typo fixes/consistency.

[ARM9] Cache code optimizations.

[ARM11] Cache code optimizations.

Don't enable the FCRAM extension if already done. Fixes fastboot chainloading itself.