Remove some invalid finals that VC++ was okay with for some reason

libaegisub/include/libaegisub/signal.h

@@ -133,7 +133,7 @@ namespace detail {
 
 	/// @brief Templated common code for signals
 	template<class Slot>
-	class SignalBaseImpl final : public SignalBase {
+	class SignalBaseImpl : public SignalBase {
 	protected:
 		typedef boost::container::map<ConnectionToken*, Slot> SlotMap;
 

src/command/vis_tool.cpp

@@ -37,7 +37,7 @@ namespace {
 	using cmd::Command;
 
 	template<class T>
-	struct visual_tool_command final : public Command {
+	struct visual_tool_command : public Command {
 		CMD_TYPE(COMMAND_VALIDATE | COMMAND_RADIO)
 
 		bool Validate(const agi::Context *c) override {

src/visual_tool.h

@@ -148,7 +148,7 @@ public:
 
 /// Visual tool base class containing all common feature-related functionality
 template<class FeatureType>
-class VisualTool final : public VisualToolBase {
+class VisualTool : public VisualToolBase {
 protected:
 	typedef FeatureType Feature;
 	typedef agi::owning_intrusive_list<FeatureType> feature_list;