START_SEC was changed in e0905e85a7ad2961aa9192f6130565860e531ad3.

Also, update the error message to mention how to format the partition at
the REPL, and make the total message shorter to save a bit of flash.

Signed-off-by: Damien George <damien@micropython.org>

This matches the esp32 port.

Because FAT is not any more the only filesystem used.

To portably get the Epoch.  This is simply aliased to localtime() on ports
that are not timezone aware.

Signed-off-by: Damien George <damien@micropython.org>

This commit changes the esp8266 boards to use littlefs v2 as the
filesystem, rather than FAT.  Since the esp8266 doesn't expose the
filesystem to the PC over USB there's no strong reason to keep it as FAT.
Littlefs is smaller in code size, is more efficient in use of flash to
store data, is resilient over power failure, and using it saves about 4k of
heap RAM, which can now be used for other things.

This is a backwards incompatible change because all existing esp8266 boards
will need to update their filesystem after installing new firmware (eg
backup old files, install firmware, restore files to new filesystem).

As part of this commit the memory layout of the default board (GENERIC) has
changed.  It now allocates all 1M of memory-mapped flash to the firmware,
so the filesystem area starts at the 2M point.  This is done to allow more
frozen bytecode to be stored in the 1M of memory-mapped flash.  This
requires an esp8266 module with 2M or more of flash to work, so a new board
called GENERIC_1M is added which has the old memory-mapping (but still
changed to use littlefs for the filesystem).

In summary there are now 3 esp8266 board definitions:
- GENERIC_512K: for 512k modules, doesn't have a filesystem.
- GENERIC_1M: for 1M modules, 572k for firmware+frozen code, 396k for
  filesystem (littlefs).
- GENERIC: for 2M (or greater) modules, 968k for firmware+frozen code,
  1M+ for filesystem (littlefs), FAT driver also included in firmware for
  use on, eg, external SD cards.

This is run with uncrustify 0.70.1, and black 19.10b0.

The ability to change the host is a frequently requested feature, so
explicitly document how it can be achieved using the existing code.

See issues #2121, #4385, #4622, #5122, #5536.

Prior to this commit, if the flash filesystem was not formatted then it
would error: "AttributeError: 'FlashBdev' object has no attribute 'mount'".
That is due to it not being able to detect the filesystem on the block
device and just trying to mount the block device directly.

This commit fixes the issue by just catching all exceptions.  Also it's not
needed to try the mount if `flashbdev.bdev` is None.

Move webrepl support code from ports/esp8266/modules into extmod/webrepl
(to be alongside extmod/modwebrepl.c), and use frozen manifests to include
it in the build on esp8266 and esp32.

A small modification is made to webrepl.py to make it work on non-ESP
ports, i.e. don't call dupterm_notify if not available.