Cleanup the buildroot

[jbrazio]

It has to start somewhere.
It has to start sometime.
What better place than here ?
What better time than now ?

-- Guerilla Radio, Rage Against the Machine.

Let's give the step forward, this PR cleans unmaintained build methods, it also addresses #3468 by removing the unused Arduino cores. Complete change list:

• Update Arduino core to 1.6.8
• Removed PlatformIOAddons
• Moved LinuxAddons to buildroot/bin
• Removed ArduinoAddons
• Removed duplicate license file Documentation\COPYING.md
• Moved .astylerc to buildroot/etc
• Updates travis for the new buildroot environment

[jbrazio]

I have build a list of "supported" boards which means boards that are listed in boards.h, for each board I found which are the micro-controller restrictions, required Arduino core and some miscellaneous notes.

You may see the information here: https://goo.gl/gFpujH
Remember this is a work in progress.

[thinkyhead]

Will this affect users who would like to flout the Arduino 1.5.x requirement and build on Linux with an older tool-set anyway?

[jbrazio]

No.. actually those users will always need to comment the #error directive otherwise they will never compile with an old IDE. The good news is that people do upgrade their Arduino IDE, you'll be able to see this once I publish the results of the survey.