Rewrote DelayUs, should yield much more accurate delays (when delay is small).
Error will still keep accumulating (but at a far lesser rate), if larger delays are needed.
Tested with two delays:
100us yielded 105-107us.
1000us (1ms) yielded 1114us
Made the assumption that TBLPTR must be set only once when the whole flash memory is written at one go.
This is not correct, when writing the last word and starting the flash buffer write, TBLPTR is NOT incremented internally (for whatever insane reason).
Address must be set after the last word has been clocked.