add new format make target

Makefile.am

@@ -77,6 +77,7 @@ noinst_HEADERS = strophepp.h
 pkgconfig_DATA = libstrophe.pc
 
 EXTRA_DIST = \
+	_clang-format \
 	Doxyfile \
 	GPL-LICENSE.txt \
 	LICENSE.txt \
@@ -203,3 +204,8 @@ tests_test_stanza_SOURCES = tests/test_stanza.c
 tests_test_stanza_CFLAGS = $(STROPHE_FLAGS)
 tests_test_stanza_LDADD = $(STROPHE_LIBS)
 tests_test_stanza_LDFLAGS = -static
+
+format:
+	@echo "   * run clang-format on all sources"
+	@dos2unix -q src/*.[ch] *.h tests/*.[ch] examples/*.c
+	@clang-format -i src/*.[ch] *.h tests/*.[ch] examples/*.c

_clang-format

@@ -0,0 +1,17 @@
+---
+AlignConsecutiveAssignments: 'false'
+AlignEscapedNewlines: Left
+AllowShortBlocksOnASingleLine: 'true'
+AllowShortFunctionsOnASingleLine: Empty
+AllowShortIfStatementsOnASingleLine: 'false'
+BinPackParameters: 'false'
+BreakBeforeBraces: Linux
+ColumnLimit: '80'
+DerivePointerAlignment: 'false'
+IndentWidth: '4'
+PointerAlignment: Right
+SortIncludes: 'false'
+TabWidth: '4'
+UseTab: Never
+
+...