Documentation/NuttShell.html:  Document the mkfatfs the -r option which can be used to specify the number of entries in the FAT12/FAT16 root directory.

Back out part of f4bcaa4f.If CONFIG_ARCH_IDLE_CUSTOM is defined, then it should not use the version of lc823450_idle.c in arch/arm/src/lc823450. That part was correct before the PR. If CONFIG_ARCH_IDLE_CUSTOM, then the build should use a custom IDLE loop in the board src/ directory.

arch/arm/src/lc823450: Fix some recently introduced build issues

Reported-by: Wig Cheng <wig.cheng@relajet.com>
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Clean up some spacing in the last commit... Seemed like a good idea at the time, but it is better to be consisten than better.

libc/unistd:  Initial, minimal implementation of sysconf().  Only sufficient to support the functionality of less standard getdtabilesize().

Squashed commit of the following:

    configs/*/README.txt: Replace each occurrence of './configure.sh' with 'tools/configure.sh'
    configs/*/README.txt:  Remove 'cd ..' after each './configure.sh'
    configs/*/README.txt:  Remove 'cd -' after each './configure.sh'
    configs/*/README.txt:  Remove 'cd tools' before each './configure.sh'
    configs/README.txt:  Remove instruction to CD tools/ before running configure.sh.

configs/teensy-3.x/usbnsh:  Remove CONFIG_USBDEV_DUALSPEED from configuration.  Hardware supports only FS.

arch/arm/src/lpc17xx:  Add support for ARMv7-M run time stack checking on NXP LPC17xx MCUs based on CONFIG_ARMV7M_STACKCHECK. Basically copied from stm32.

configs/freedom-k28f:  If drivers/leds/rgbled.c is enabled, then treat the board as though it had no discrete LEDs.

drivers/leds/rgbled.c:  Fix a compilation error introduced with a recent change to add multi-channel operation to RGB LED driver.

configs/freedom-k28f:  With these changes to the configuration, the NSH configuration is now functional on the k28f board.  Also fixes corrects the active logic level for the RGB LED.   arch/arm/src/kinetis/chip:  Fixes an error in vector configuration.

arch/arm/src/nrf52/nrf52_flash.c:  Add missing erasesize method.  Add missing function header comments.

libc/libc.csv: Fix missing or duplicate quotation marks.  mksymtab was not able to parse libc/libc.csv due to missing or duplicate quotation marks.

    configs/freedom-k28f:  Add button and LED support.
    arch/arm/src/kinetis:  Fix a couple of additional compile problems.
    arch/arm/src/kinetis/chip and configs/freedom-k28f:  Add things needed for a successful build.  Still need board LED definitions.

     arch/arm/src/kinetis:  The K28F Kinetis MPU is almost the same as the K66F MPU.
     arch/arm/src/kinetis:  The K28F Kinetis FMC is the same as the K66F FMC.

configs/photon: Adds RGB led support

Approved-by: Gregory Nutt <gnutt@nuttx.org>

drivers/sensors: Adds support for INA3221 power sensor. This has a 3 channel bus/shunt voltage pairs.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

drivers/rgbled: Adds support for multichannel PWM (multiple PWM channels on a single timer)

Approved-by: Gregory Nutt <gnutt@nuttx.org>