Use platform.local.txt to add -Werror to GCC for the build of all
code. Any warnings on a submitted patch will cause an error.
Several examples and libraries had warnings/errors (missing returns
on functions, types, etc.). Clean those up with this commit as well.
* Add option to give ArduinoOTA a hashed value of the password
hashed password can be safely stored on flash
* Switch to separate method to accept the hash
* Calculate the hash of plain passwords at setup
* missed line
* Remove underscores from local variable
