libc/lzf:  lzf_compress() now expects the hash table as user allocated input parmeter rather than declaring the huge array on the stack.

(cherry picked from commit ea77dfafe1afe7d399e47871d2ec81fea99626cc)

(cherry picked from commit 8879116fe85558520c4811dc4ab780b28e66810d)

drivers/serial/Kconfig:  Kconfig is too big, divide into Kconfig, Kconfig-uart, Kconfig-usart, Kconfig-sci, Kconfig-16550.  More than one MCU supports LPUARTs.  Add Kconfig-lpuart and remove MCU-specific LPUART definitions.  Affects Kinetis and STM32L4.

arch/arm/src/stm32/lowputc: fix uart glitch when lowputc is enabled

Calling up_lowputc() when a character is in the shift register results
in corrupted character on stm32f1xx and stm32f205 cores.
TC status bit ensures that up_lowputc() waits for an on-going
transmission to complete before writing in TDR.

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

stm32f103-minimum: add support for DFU bootloader

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

net/tcp:  In tcp_input(), add the logic to detect, decode, and respond to TCP Keep-Alive packets.  In tcp_timer(), fix some problems with the way that TCP Keep-Alive probes were being formatted.

arch/arm/src/stm32/usb: skip recipient check for descriptor related requests

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

    net/tcp:  Add logic to send probes when SO_KEEPALIVE is enabled.
    net/tcp:  TCP socket should not have to be connected to configure KeepAlive.
    net/: Add a separate configuration to enable/disable KEEPALIVE socket options.
    net/tcp: Arguments to TCP keep-alive timing functions probably should be struct timeval as are the times for other time-related socket options.
    net/tcp:  Fix a backward conditional
    net/tcp:  Add some more checks and debug output to TCP-protocol socket options.
    net/tcp:  Cosmetic changes to some alignment.
    net/:  Adds socket options needed to manage TCP-keepalive and TCP state machine logic to detect if that the remote peer is alive.  Still missing the timer poll logic to send the keep-alive probes and the state machine logic to respond to probes.

drivers/lcd/ft80x:  Fix a typo that caused the driver to fail to recognize the ft801 chip version. Also update an unrelated README file.

    drviers/lcd/ft80x:  No longer depends on CONFIG_EXPERIMENTAL
    Update README.txt