Add clang-format file

Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.

Servers/WindowServer/WSCompositor.h

@@ -10,7 +10,14 @@
 class Painter;
 class WSCursor;
 
-enum class WallpaperMode { Simple, Tile, Center, Scaled, Unchecked };
+enum class WallpaperMode
+{
+    Simple,
+    Tile,
+    Center,
+    Scaled,
+    Unchecked
+};
 
 class WSCompositor final : public CObject {
 public: