windowmanager destructor free _mainwindow, fix save - remove const in (#36)

* windowmanager destructor free _mainwindow, fix save - remove const in
settingsPath that is being written to from ptree tree

* syntax error

* remove destructor, singleton, let OS claim the resource as no special cleanup of _mainWindow is not needed

messages/messagebuilder.h

@@ -2,6 +2,7 @@
 #define MESSAGEBUILDER_H
 
 #include "messages/message.h"
+#include <ctime>
 
 namespace chatterino {
 namespace messages {

platform/borderless/winnativewindow.h

@@ -1,6 +1,7 @@
 #ifndef WINNATIVEWINDOW_H
 #define WINNATIVEWINDOW_H
 
+#define NOMINMAX
 #include "Windows.h"
 #include "Windowsx.h"
 

usermanager.h

@@ -4,6 +4,7 @@
 #include "twitch/twitchuser.h"
 
 #include <mutex>
+#include <vector>
 
 namespace chatterino {
 

widgets/mainwindow.cpp

@@ -10,6 +10,7 @@
 #include <boost/foreach.hpp>
 
 #ifdef USEWINSDK
+#define NOMINMAX
 #include "Windows.h"
 #endif
 

windowmanager.cpp

@@ -10,8 +10,7 @@ namespace chatterino {
 WindowManager WindowManager::instance;
 
 WindowManager::WindowManager()
-    : _windowMutex()
-    , _mainWindow(nullptr)
+    : _mainWindow(nullptr)
 {
 }
 
@@ -103,7 +102,7 @@ void WindowManager::load()
 
 void WindowManager::save()
 {
-    const auto &settingsPath = getSettingsPath();
+    auto &settingsPath = getSettingsPath();
     boost::property_tree::ptree tree;
 
     // Create windows array