fast memcpy/memset

Add delayNanoseconds()

This makes sense now, and would be useful for shorter wait-times. Could be used for PulseIn etc.  where we need defined very short delays.

fix warning "implicit declaration of function 'delay'"

Renumbered IRQ_RESERVED1-7, IRQ_SOFTWARE = 62

corrected SAI1/3_CLK_PODF

SCB_SHPR3 = 0x20000000;  // Systick = priority 32

default 128 priority for all interrupts

SPDIF register bit defs

Tempmon registers - bit definitions

Reset Control Bit Definitions

- comment SRC_GPR1..SRC_GPR10 (used by the ROM code)

Update imxrt.h

Deleted a duplicate define: #define CCM_CBCMR_PERIPH_CLK2_SEL_MASK		((uint32_t)(0x03 << 12))
 and added tempmon registers