Split up languages.h, use ISO codes

Breaking up languages.h makes it easier to translate. Using language
codes makes it easier to select a language and sets the naming standard.
Clean up, move unused to the bottom, add headings
Added example configs for printers from http://tvrrug.org.uk/
Merge pull request #1194 from boelle/Marlin_v1

Added example configs for printers from http://tvrrug.org.uk/
Merge pull request #1192 from thinkyhead/split_language

Split up languages.h. Use ISO language codes.
Defines for electronics boards

Added boards.h which contains defines for all the board numbers, plus
some shorthand macros for less typing.
Clean up configs
Merge branch 'board_defines' of https://github.com/thinkyhead/Marlin into board_defines