Added Luxembourgish translation
Removed contrib folder, renamed some folders, removed duplicate lesson 06
Renamed lesson 3
[lb] Added lesson 9
Merge pull request #2 from mweimerskirch/lessons_3_and_9

Lessons 3 and 9
[lb] Renamed some files into their Luxembourgish equivalents
[lb] translated code blocks for lessons 1 and 7 into German
[lb] Renamed markdown file for lesson 2 to luxembourgish
[lb-LU] A few tweaks and corrections + Translated code blocks to German
Merge pull request #1 from mweimerskirch/lessons_3_and_9

[lb-LU] A few tweaks and corrections + Translated code blocks to German
Lesson 9, en-GB to es-AR
Some corrections
A few typos
A few typos
Added lesson 7 (work in progress)
Lesson 7 almost finished (need review and translate Scratch scripts)
Translated scripts and fixed some typos
Added notas para coordinadores and corrected typos in main doc
Typos and notas para coordinadores translation finished
Typos