Utilize templates for Settings class

Use boost2::signals for the valueChanged signal (a LOT less messy to
        deal with than qt signals)
Remove unused settings classes (BoolSetting, FloatSetting, IntSetting,
        StringSetting)

What's left: Implement the remaining signals

settings/settings.cpp

@@ -6,13 +6,12 @@
 namespace chatterino {
 namespace settings {
 
-Settings Settings::_;
+Settings Settings::instance;
 
 Settings::Settings()
     : settings(
           QStandardPaths::writableLocation(QStandardPaths::AppDataLocation),
           QSettings::IniFormat)
-    , settingsItems()
     , portable(false)
     , wordTypeMask(messages::Word::Default)
     , theme("", "dark")
@@ -43,62 +42,61 @@ Settings::Settings()
     , windowTopMost("", true)
     , hideTabX("", false)
 {
-    settingsItems.reserve(25);
-    settingsItems.push_back(&theme);
-    settingsItems.push_back(&user);
-    settingsItems.push_back(&emoteScale);
-    settingsItems.push_back(&scaleEmotesByLineHeight);
-    settingsItems.push_back(&showTimestamps);
-    settingsItems.push_back(&showTimestampSeconds);
-    settingsItems.push_back(&showLastMessageIndicator);
-    settingsItems.push_back(&allowDouplicateMessages);
-    settingsItems.push_back(&linksDoubleClickOnly);
-    settingsItems.push_back(&hideEmptyInput);
-    settingsItems.push_back(&showMessageLength);
-    settingsItems.push_back(&seperateMessages);
-    settingsItems.push_back(&mentionUsersWithAt);
-    settingsItems.push_back(&allowCommandsAtEnd);
-    settingsItems.push_back(&enableHighlights);
-    settingsItems.push_back(&enableHighlightSound);
-    settingsItems.push_back(&enableHighlightTaskbar);
-    settingsItems.push_back(&customHighlightSound);
-    settingsItems.push_back(&enableTwitchEmotes);
-    settingsItems.push_back(&enableBttvEmotes);
-    settingsItems.push_back(&enableFfzEmotes);
-    settingsItems.push_back(&enableEmojis);
-    settingsItems.push_back(&enableGifAnimations);
-    settingsItems.push_back(&enableGifs);
-    settingsItems.push_back(&inlineWhispers);
-    settingsItems.push_back(&windowTopMost);
-    settingsItems.push_back(&hideTabX);
+    settingsItems.push_back(theme);
+    settingsItems.push_back(user);
+    settingsItems.push_back(emoteScale);
+    settingsItems.push_back(scaleEmotesByLineHeight);
+    settingsItems.push_back(showTimestamps);
+    settingsItems.push_back(showTimestampSeconds);
+    settingsItems.push_back(showLastMessageIndicator);
+    settingsItems.push_back(allowDouplicateMessages);
+    settingsItems.push_back(linksDoubleClickOnly);
+    settingsItems.push_back(hideEmptyInput);
+    settingsItems.push_back(showMessageLength);
+    settingsItems.push_back(seperateMessages);
+    settingsItems.push_back(mentionUsersWithAt);
+    settingsItems.push_back(allowCommandsAtEnd);
+    settingsItems.push_back(enableHighlights);
+    settingsItems.push_back(enableHighlightSound);
+    settingsItems.push_back(enableHighlightTaskbar);
+    settingsItems.push_back(customHighlightSound);
+    settingsItems.push_back(enableTwitchEmotes);
+    settingsItems.push_back(enableBttvEmotes);
+    settingsItems.push_back(enableFfzEmotes);
+    settingsItems.push_back(enableEmojis);
+    settingsItems.push_back(enableGifAnimations);
+    settingsItems.push_back(enableGifs);
+    settingsItems.push_back(inlineWhispers);
+    settingsItems.push_back(windowTopMost);
+    settingsItems.push_back(hideTabX);
 
-    QObject::connect(&showTimestamps, &BoolSetting::valueChanged, this,
-                     &Settings::updateWordTypeMask);
-    QObject::connect(&showTimestampSeconds, &BoolSetting::valueChanged, this,
-                     &Settings::updateWordTypeMask);
-    QObject::connect(&enableBttvEmotes, &BoolSetting::valueChanged, this,
-                     &Settings::updateWordTypeMask);
-    QObject::connect(&enableEmojis, &BoolSetting::valueChanged, this,
-                     &Settings::updateWordTypeMask);
-    QObject::connect(&enableFfzEmotes, &BoolSetting::valueChanged, this,
-                     &Settings::updateWordTypeMask);
-    QObject::connect(&enableTwitchEmotes, &BoolSetting::valueChanged, this,
-                     &Settings::updateWordTypeMask);
+    this->showTimestamps.valueChanged.connect(
+        [this](const auto &) { this->updateWordTypeMask(); });
+    this->showTimestampSeconds.valueChanged.connect(
+        [this](const auto &) { this->updateWordTypeMask(); });
+    this->enableBttvEmotes.valueChanged.connect(
+        [this](const auto &) { this->updateWordTypeMask(); });
+    this->enableEmojis.valueChanged.connect(
+        [this](const auto &) { this->updateWordTypeMask(); });
+    this->enableFfzEmotes.valueChanged.connect(
+        [this](const auto &) { this->updateWordTypeMask(); });
+    this->enableTwitchEmotes.valueChanged.connect(
+        [this](const auto &) { this->updateWordTypeMask(); });
 }
 
 void
 Settings::save()
 {
-    for (Setting *item : settingsItems) {
-        item->save(settings);
+    for (auto &item : settingsItems) {
+        item.get().save(settings);
     }
 }
 
 void
 Settings::load()
 {
-    for (Setting *item : settingsItems) {
-        item->load(settings);
+    for (auto &item : settingsItems) {
+        item.get().load(settings);
     }
 }
 
@@ -109,7 +107,7 @@ Settings::isIgnoredEmote(const QString &)
 }
 
 void
-Settings::updateWordTypeMask(bool)
+Settings::updateWordTypeMask()
 
 {
     using namespace messages;
@@ -143,5 +141,6 @@ Settings::updateWordTypeMask(bool)
     emit wordTypeMaskChanged();
     //    }
 }
-}
-}
+
+}  // namespace settings
+}  // namespace chatterino