Discern between virtual and abstract class bindings

* Previous "virtual" classes (which can't be instantiated) are not corretly named "abstract".
* Added a new "virtual" category for classes, they can't be instantiated from the editor, but can be inherited from script and extensions.
* Converted a large amount of classes from "abstract" to "virtual" where it makes sense.

Most classes that make sense have been converted. Missing:

* Physics servers
* VideoStream
* Script* classes.

which will go in a separate PR due to the complexity involved.

4 files changed, 11 insertions, 3 deletions

diff --git a/scene/gui/range.cpp b/scene/gui/range.cpp
index 879f25c8d8..2fb6452a97 100644
--- a/scene/gui/range.cpp
+++ b/scene/gui/range.cpp
@@ -40,6 +40,9 @@ TypedArray<String> Range::get_configuration_warnings() const {
 	return warnings;
 }
 
+void Range::_value_changed(double p_value) {
+	GDVIRTUAL_CALL(_value_changed, p_value);
+}
 void Range::_value_changed_notify() {
 	_value_changed(shared->val);
 	emit_signal(SNAME("value_changed"), shared->val);
@@ -279,6 +282,8 @@ void Range::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "allow_greater"), "set_allow_greater", "is_greater_allowed");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "allow_lesser"), "set_allow_lesser", "is_lesser_allowed");
 
+	GDVIRTUAL_BIND(_value_changed);
+
 	ADD_LINKED_PROPERTY("min_value", "value");
 	ADD_LINKED_PROPERTY("min_value", "max_value");
 	ADD_LINKED_PROPERTY("min_value", "page");
diff --git a/scene/gui/range.h b/scene/gui/range.h
index c27eeee13c..597c50ca26 100644
--- a/scene/gui/range.h
+++ b/scene/gui/range.h
@@ -62,12 +62,14 @@ class Range : public Control {
 	void _validate_values();
 
 protected:
-	virtual void _value_changed(double) {}
+	virtual void _value_changed(double p_value);
 
 	static void _bind_methods();
 
 	bool _rounded_values = false;
 
+	GDVIRTUAL1(_value_changed, double)
+
 public:
 	void set_value(double p_val);
 	void set_min(double p_min);
diff --git a/scene/gui/spin_box.cpp b/scene/gui/spin_box.cpp
index 5fd31c5416..e50d7e765c 100644
--- a/scene/gui/spin_box.cpp
+++ b/scene/gui/spin_box.cpp
@@ -39,7 +39,7 @@ Size2 SpinBox::get_minimum_size() const {
 	return ms;
 }
 
-void SpinBox::_value_changed(double) {
+void SpinBox::_value_changed(double p_value) {
 	String value = TS->format_number(String::num(get_value(), Math::range_step_decimals(get_step())));
 	if (!prefix.is_empty()) {
 		value = prefix + " " + value;
@@ -48,6 +48,7 @@ void SpinBox::_value_changed(double) {
 		value += " " + suffix;
 	}
 	line_edit->set_text(value);
+	Range::_value_changed(p_value);
 }
 
 void SpinBox::_text_submitted(const String &p_string) {
diff --git a/scene/gui/spin_box.h b/scene/gui/spin_box.h
index 0691a4b48d..a15e3fe5f5 100644
--- a/scene/gui/spin_box.h
+++ b/scene/gui/spin_box.h
@@ -47,7 +47,7 @@ class SpinBox : public Range {
 	void _release_mouse();
 
 	void _text_submitted(const String &p_string);
-	virtual void _value_changed(double) override;
+	virtual void _value_changed(double p_value) override;
 	void _text_changed(const String &p_string);
 
 	String prefix;