Changes:

New target - KL27Z_IAR
New target - MAX32620HSP_ARM_STD
New target - MAX32620HSP_GCC_ARM
New target - MAX32620HSP_IAR
New target - NCS36510_ARM_STD
New target - NCS36510_GCC_ARM
New target - NCS36510_IAR

STM32F3 family : Add and enable asynchronous serial, plus tests.
STM32L4 family : Add and enable asynchronous serial, plus tests.
Fixing issue where GCC fails to report compile errors when non-verbose.
RZ_A1H - Enable SPI1 on pins P6_4 to P6_7.
KL27Z : SPI driver bug fixes and Improvements, ARM linker file update.
STM32F4, STM32F7 families : Add entropy functions, documentation, code improvements, fix build issues.
HEXIWEAR: Update I2C pin mapping, Add support to create KDS projects.
SingletonPtr bugfixes.
Beetle: Implement sleep API.
STM32F3 : fix RTOS IAR test, RTOS GCC_ARM test.
nrf5x : Introduce uart hardware flow control configuration.
K64F/K22F: Implement HAL lp_timer API.
Ticker: Move ticker initialisation to object creation time.
STM32F4 : remove printf from pwmout
NXP : Fix multiple definition errors in GCC_CR build,  fix linker errors.
Add TOOLCHAIN_GCC_CR support.
STM32L1 family : Add and enable asynchronous serial, plus tests.
NUC472 : Fix Ethernet wrong INT status in RX_Action.
NUCLEO : Use GCC small build for 64K flash STM32.
STM32F2 family : Add and enable asynchronous serial, plus tests.
K64F: Revert to hardcoded stack pointer in RTX .
Tests : New ones added and some updates to existing.