Make mapping WASD less intimidating

replacing key_mapping.lua with key_mapping.txt to make it less
intimidating. As most people know how to open text files and may not
realise you can open lua files in the same way.
Merge pull request #79 from MarkL1961/WASD

Make mapping WASD less intimidating
Norwegian translation
Merge pull request #82 from Grimdoc/Translation

Norwegian translation update