Part 1: Split IWRAM into iwram_data and iwram_smc_data. For now, these areas are simply splits of the old 64 KiB section whose first 32 KiB section was self-modifying code (SMC) detection data.

Stop reading a byte, half-word or word to compare it with a value that is about to be written. Simply write it and let that trigger flushes.

Also, (DSTwo-specific) DMA modification statistics are gone.

The document I'm using to implement the upcoming changes is also committed.