Build a single INO under a Windows VM on Travis to ensure
that the Win32 toolchain works properly.
In build.py, instead of making a string with spaces and then
splitting on " ", just make the list itself with individual parameters.
This will allow spaces in paths to be supported properly.
* Move all scripts and documentation to Python3
Python 2 EOL is Jan 1, 2020. Migrate scripts to run under Python 3.
Under Windows, we're already running Python 3.7, by dumb luck. The
oddness is that the Windows standalone executable for Python 3 is called
"python" whereas under UNIX-like OSes it's called "python3" with
"python" always referring to the Python 2 executable. The ZIP needs to
be updated to include a Python3.exe (copy of Python.exe) so that we can
use the same command lines under Linux and Windows, and to preserve my
sanity.
Fixes#6376
* Add new Windows ZIP with python3.exe file
* Sort options in boards.txt generation for repeatability
The order of the board opts dict changes depending on the Python version
and machine, so sort the options before printing them to get a stable
ordering.
* Re-add Python2 compatibility tweaks
Most scripts can run as Python 2 or Python 3 with minimal changes, so
re-add (and fix, as necessary) compatibility tweaks to the scripts.
boards generator updates:
* simplified mapping description: only flash and spiffs sizes are needed
* some ldscripts are renamed due to autogenerated names
* +2M/0, +2M/512K spiffs, +4M0
* reduce length of hidden strings in boards.txt (#5100, https://github.com/arduino/arduino-builder/issues/284)
* give more details in ldscripts (address, size, +rf-cal, +sdk-wifi-settings)
