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/source/multithreadedwaitablemanager.cpp

@@ -1,6 +1,7 @@
 #include <switch.h>
 
 #include <algorithm>
+#include <functional>
 
 #include <stratosphere/multithreadedwaitablemanager.hpp>
 
@@ -44,21 +45,15 @@ IWaitable *MultiThreadedWaitableManager::get_waitable() {
         rc = svcWaitSynchronization(&handle_index, handles.data(), this->waitables.size(), this->timeout);
         IWaitable *w = this->waitables[handle_index];
         if (R_SUCCEEDED(rc)) {
-            for (int i = 0; i < handle_index; i++) {
-                this->waitables[i]->update_priority();
-            }
+            std::for_each(waitables.begin(), waitables.begin() + handle_index, std::mem_fn(&IWaitable::update_priority));
             this->waitables.erase(this->waitables.begin() + handle_index);
         } else if (rc == 0xEA01) {
             /* Timeout. */
-            for (auto & waitable : this->waitables) {
-                waitable->update_priority();
-            }
+            std::for_each(waitables.begin(), waitables.end(), std::mem_fn(&IWaitable::update_priority));
         } else if (rc != 0xF601 && rc != 0xE401) {
             /* TODO: Panic. When can this happen? */
         } else {
-            for (int i = 0; i < handle_index; i++) {
-                this->waitables[i]->update_priority();
-            }
+            std::for_each(waitables.begin(), waitables.begin() + handle_index, std::mem_fn(&IWaitable::update_priority));
             this->waitables.erase(this->waitables.begin() + handle_index);
             delete w;
         }
@@ -107,4 +102,4 @@ void MultiThreadedWaitableManager::thread_func(void *t) {
             }
         }
     }
-}
+}