style: reformat C/C++ sources and headers with clang-format

Run clang-format over all project C/C++ source and header files
(.c, .cpp, .cc, .h, .hpp, .hh, .m, .mm) under app/ and tests/.
Non-source files (svg, qm, qrc, etc.) were not touched.

tests/gtest/common_xmlutils_test.cpp

@@ -59,7 +59,6 @@ TEST(CommonXmlUtils, ReadNextStartElementSkipsUnknown)
 	EXPECT_EQ(reader.name().toString(), QStringLiteral("known"));
 }
 
-
 TEST(CommonXmlUtils, ReadNextStartElementWithCancel)
 {
 	QByteArray xml = "<root><child/></root>";