Add missing NSH configuration settings.  Correct some conditional logic for STM32 FALSH pre-fetch settings.  From Lorenz Meier

Move SAM3U header files to arch/arm/src/sam3u/chip. Some renaming of SAM3U to SAM to ssupport SAM4.  Convert all configs/sam3u-ek configurations to use the kconfig-frontends tool

Upate .gitignore files.  Add .dSYM. Make sure / is present where needed.  Add some missing .gitignore files

Rename SLCD geometry tructure to attributes;  Move MAX contrast to attributes.  Add  attribute and ioctl commands to get and set SLCD brightness

PCB-Logic PIC32MX LCD1602 driver now supports SLCD CODED; Added an SLCD ioctl command to get cursor position

Converted configs/pcblogic-pic32mx configurations to use kconfig-frontends.  Re-organization of files in configs/pcblogic-pic32mx/src

Additional bug fixes and minor extensions to the STM32L-Disovery segment LCD support and to the apps/examples/slcd segment LCD test.

Add apps/examples/slcd, Remove USB from STM32L-Discovery, LSE support for the STM32 L family, some STM32L-Discovery LCD debug changes

Fix STM32L15X vector definitions; Fix STM32L-Discovery LED controls.  The NSH configuration is now fully functional on the STM32L-Discovery board.

apps/examples/helloxx entry point name was mangled when built as an NSH builtin; plus some README updates

Default NxWidgets and NxWM priorities should be 100 not 50 to be consistent with other default priorities

Rearchitecting of some MTD, partition, SMART interfaces, and FLASH drivers to:  Better use the byte write capbility when available and to use smaller erase sectors for the erase sector size when available).

Add support for the byte write method to MTD partition logic;  Beef up the MTD partition test -- and fix resulting bugs detected

Various Kconfig files still have references to CONFIG_ variables.  Some in harmless comments, some in config definionts which is not harmless.  All removed