all: Prune trailing whitespace.

Prune trailing whitespace across the whole project (almost), done
automatically with:

    grep -IUrl --color "[[:blank:]]$" --exclude-dir=.git --exclude=*.exp |\
        xargs sed -i 's/[[:space:]]*$//'

Exceptions:
- Skip third-party code in lib/ and drivers/cc3100/
- Skip generated code in bluetooth_init_cc2564C_1.5.c
- Preserve command output whitespace in docs, eg:
  docs/esp8266/tutorial/repl.rst

Signed-off-by: Phil Howard <phil@gadgetoid.com>

docs/develop/gettingstarted.rst

@@ -112,7 +112,7 @@ Check that you have Python available on your system:
 .. code-block:: bash
 
    $ python3
-   Python 3.5.0 (default, Jul 17 2020, 14:04:10) 
+   Python 3.5.0 (default, Jul 17 2020, 14:04:10)
    [GCC 5.4.0 20160609] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>>