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/subset_preconditioner.cc

@@ -32,6 +32,7 @@
 
 #include <memory>
 #include <string>
+
 #include "ceres/compressed_row_sparse_matrix.h"
 #include "ceres/inner_product_computer.h"
 #include "ceres/linear_solver.h"
@@ -50,8 +51,7 @@ SubsetPreconditioner::SubsetPreconditioner(
   LinearSolver::Options sparse_cholesky_options;
   sparse_cholesky_options.sparse_linear_algebra_library_type =
       options_.sparse_linear_algebra_library_type;
-  sparse_cholesky_options.use_postordering =
-      options_.use_postordering;
+  sparse_cholesky_options.use_postordering = options_.use_postordering;
   sparse_cholesky_ = SparseCholesky::Create(sparse_cholesky_options);
 }