Add forgotten changes for "Port SPI and dependant things to the Service design.".
Implement SD card buffer sizes not being a multiple of block size.
AvrSpi: Implement configuration of the SPI speed.
Increase default SPI speed on AVR.
Change buffer allocations on ramps13 and megatronics3.

For more speed in exchange for less lookahead and less SD buffer. AVRs are having problems with underruns.