Modernize src/c* src/d* and src/e* files (#6263)

* Modernize src/c* src/d* and src/e* files

* default operator
* redundant init
* delete default constructors on CraftDefinition childs (never used)
* fix some missing init values
* const ref fix reported by clang-tidy
* ranged-based for loops
* simple conditions & returns
* empty stl function instead of size
* emplace_back stl function instead of push_back + construct temp obj
* auto for some iterators
* code style fixes
* c++ stl headers instead of C stl headers (stdio.h -> cstdio)

src/defaultsettings.cpp

@@ -440,8 +440,7 @@ void set_default_settings(Settings *settings)
 void override_default_settings(Settings *settings, Settings *from)
 {
 	std::vector<std::string> names = from->getNames();
-	for (size_t i = 0; i < names.size(); i++) {
-		const std::string &name = names[i];
+	for (const auto &name : names) {
 		settings->setDefault(name, from->get(name));
 	}
 }