Advanced channel filters (#1748)

Adds custom channel filters complete with their own mini-language. Filters can be created in settings, and applied by clicking the three dots to open the Split menu and selecting "Set filters".

src/widgets/splits/SplitHeader.cpp

@@ -327,6 +327,7 @@ std::unique_ptr<QMenu> SplitHeader::createMainMenu()
                     QKeySequence("Ctrl+N"));
     menu->addAction("Search", this->split_, &Split::showSearch,
                     QKeySequence("Ctrl+F"));
+    menu->addAction("Set filters", this->split_, &Split::setFiltersDialog);
     menu->addSeparator();
 #ifdef USEWEBENGINE
     this->dropdownMenu.addAction("Start watching", this, [this] {
@@ -700,6 +701,11 @@ void SplitHeader::updateChannelText()
         }
     }
 
+    if (!title.isEmpty() && this->split_->getFilters().size() != 0)
+    {
+        title += " - filtered";
+    }
+
     this->titleLabel_->setText(title.isEmpty() ? "<empty>" : title);
 }