ChangeLog

	* nuttx/lcd/hd4478ou.h and configs/pcblogic-pic32mx/src/up_lcd1602:
	  Start of support of LCD1602 alphanumeric LCD.  I need a few
	  more parts before I can finish integrating this one.
	* arch/arm/src/*/chip.h and arch/arm/include/*/chip.h:  Move all
	  priority ranges from the src to the include chip.h header file.
	* arch/arm/include/armv7-m/irq.h:  Add inline functions to enable
	  and disable interrupts via the BASEPRI register.
	* arch/arm/Kconfig:  Add new option CONFIG_ARM7VM_USEBASEI
	* arch/arm/src/*/*_irq.c:  Set the priority of the SVCALL exception
	  to the highest possible value.
	* arch/armv7-m/up_hardfault.c:  Fail if a hardfault occurs
	  while CONFIG_ARM7VM_USEBASEPRI=y.
	* arch/arm/src/stm32/stm32_serial.c:  Add support for USART
	  single wire more (Contributed by the PX4 team).
	* sched/: Implement support for retaining child task status after
	  the child task exists.  This is behavior required by POSIX.
	  But in NuttX is only enabled with CONFIG_SCHED_HAVE_PARENT and
	  CONFIG_SCHED_CHILD_STATUS