ErikZalm/Marlin — pull request #1222 by RobotCaleb (2014-12-21 22:17:35+00:00)
Title: Language change implementation revamped. Didn't work as intended with Arduino IDE

Using the new language implementation wasn't behaving as expected.

No matter what LANGUAGE_CHOICE was set to it would always take the en branch.
I revamped it a bit to use a macro to create the language include file name. This required a slight tweak to the RU declaration since it's special-cased in a couple places in code.