Modernize: Use range-based for loops for readability (#762)

Also run clang-format on these files as requested

src/ostream_wrapper.cpp

@@ -31,8 +31,8 @@ void ostream_wrapper::write(const std::string& str) {
     std::copy(str.begin(), str.end(), m_buffer.begin() + m_pos);
   }
 
-  for (std::size_t i = 0; i < str.size(); i++) {
-    update_pos(str[i]);
+  for (char ch : str) {
+    update_pos(ch);
   }
 }