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.
Use unique name values in library.properties for the esp8266 libraries
that are also Arduino IDE Built-In libraries. This solves the issue of
SD and Servo libraries always appearing as Type: Updatable in the
Arduino IDE 1.6.6 Library Manager when an esp8266 board is selected.