Changes to allow for SPI communication. MTS_SPI_Slave.cpp replaces MTSSerial.cpp. AT_SPI_Slave.ccp replaces ATSerial.cpp.

Dependencies:   MTS_SPI libmDot-dev-mbed5-deprecated

Fork of Dot-AT-Firmware by MultiTech

mts_at_version.h/shortlog@e20116281a78: not found in manifest