fix formatting for (non-generated) internal source files

- Change formatting standard to Cpp11. Main difference is not having
  the space between two closing >> for nested templates. We don't
  choose c++14, because older versions of clang-format (version 9
  and earlier) don't know this value yet, and it doesn't make a
  difference in the formatting.
- Apply clang-format to all (non generated) internal source files.
- Manually fix some code sections (clang-format on/off) and c-strings
- Exclude some embedded external files with very different formatting
  (gtest/gmock)
- Add script to format all source files

Change-Id: Ic6cea41575ad6e37c9e136dbce176b0d505dc44d

internal/ceres/cxsparse.cc

@@ -33,13 +33,12 @@
 
 #ifndef CERES_NO_CXSPARSE
 
-#include "ceres/cxsparse.h"
-
 #include <string>
 #include <vector>
 
 #include "ceres/compressed_col_sparse_matrix_utils.h"
 #include "ceres/compressed_row_sparse_matrix.h"
+#include "ceres/cxsparse.h"
 #include "ceres/triplet_sparse_matrix.h"
 #include "glog/logging.h"