Add clang-format configuration, clean up

.clang-format

@@ -0,0 +1,37 @@
+# clang-format is fairly limited, and these rules are approximate:
+#  - array initializers can get terribly mangled with clang-format 12.0,
+#  - sometimes it still aligns with space characters,
+#  - struct name NL { NL ... NL } NL name; is unachievable.
+BasedOnStyle: GNU
+ColumnLimit: 80
+IndentWidth: 4
+TabWidth: 4
+UseTab: ForContinuationAndIndentation
+BreakBeforeBraces: Allman
+SpaceAfterCStyleCast: true
+AlignConsecutiveAssignments: true
+AlignAfterOpenBracket: DontAlign
+AlignEscapedNewlines: DontAlign
+AlignOperands: DontAlign
+AlignConsecutiveMacros: Consecutive
+AllowAllArgumentsOnNextLine: false
+AllowAllParametersOfDeclarationOnNextLine: false
+Cpp11BracedListStyle: true
+MaxEmptyLinesToKeep: 2
+
+# IncludeCategories has some potential, but currently it breaks build.
+# Note that the documentation says the value should be "Never".
+SortIncludes: false
+
+# Must be kept synchronized with gi18n.h and make-template.sh.
+WhitespaceSensitiveMacros: ['_', 'Q_', 'N_', 'C_', 'NC_']
+
+# This is a compromise, it generally works out aesthetically better.
+BinPackArguments: false
+
+# Unfortunately, this doesn't work for block comments, used in logdiag.
+SpacesBeforeTrailingComments: 2
+
+# logdiag-specific function body wrappers.
+MacroBlockBegin: "LD_LUA_CAIRO_BEGIN"
+MacroBlockEnd: "LD_LUA_CAIRO_END"