Modernize C++ usage (#144)

* Stratosphere: Use modern C++ idioms in some places

* algorithms like std::for_each are used instead of raw loops

* Stratosphere: Replace more raw loops with algorithms

* Stratosphere: Add a utility predicate function to test for equality with a reference element

This can be used to rewrite some common raw loops using algorithms instead

* fs.mitm: Use variant

* fs.mitm: Use enum class

* fs.mitm: Turn RomFSSourceInfo::Cleanup into a destructor

This obsoletes the need for a custom deleter in other places

* fs.mitm: Use enum class some more

* fs.mitm: Use unique_ptr

* fs.mitm: Simplify initialization

* Stratosphere: Simplify initialization

* fs.mitm: Use unique_ptr (fix memory leak along the way)

The previous code was using "delete" rather than "delete[]"

* fs.mitm: Use vector::emplace_back rather than push_back

emplace_back constructs elements in-place, hence avoiding a redundant element copy.

* Stratosphere: Replace more raw loops with algorithms

* Stratosphere: Use unique_ptr

* fs.mitm: Replace more raw loops with algorithms

* Stratosphere: Prefer move-construction over copy-construction when moving sink parameters around

stratosphere/libstratosphere/include/meta_tools.hpp

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <functional>
+
+namespace detail {
+
+template<typename T>
+struct class_of;
+
+template<typename Ret, typename C>
+struct class_of<Ret C::*> {
+    using type = C;
+};
+
+template<typename T>
+using class_of_t = typename class_of<T>::type;
+
+template<typename Mem, typename T, typename C = class_of_t<Mem>>
+struct member_equals_fn_helper {
+    T ref;
+    Mem mem_fn;
+
+    bool operator()(const C& val) const {
+        return (std::mem_fn(mem_fn)(val) == ref);
+    }
+
+    bool operator()(C&& val) const {
+        return (std::mem_fn(mem_fn)(std::move(val)) == ref);
+    }
+};
+
+} // namespace detail
+
+template<typename Mem, typename T>
+auto member_equals_fn(Mem mem, T ref) {
+    return detail::member_equals_fn_helper<Mem, T>{std::move(ref), std::move(mem)};
+}