Update CodingStyle snipped to use initializer list with QStringList & .clang-format file

Considering that this project has a very specific coding style it is best to ship a clang-format file, which will allow the devs to get at least some degree of automatic formatting.

Not sure if you want the AlwaysBreakAfterReturnType option set to TopLevel. See https://clang.llvm.org/docs/ClangFormatStyleOptions.html (personally I am not a fan of it)

Also the line column limit is set to 160, which is the KDE default. In the codebase the 100 char limit seems to be ignored quite often.