Give a layout name to math HullInset

This makes it accessible to inset-forall.

(cherry picked from commit f4a3f4f29b)

src/mathed/InsetMathHull.cpp

@@ -217,6 +217,12 @@ InsetMathHull & InsetMathHull::operator=(InsetMathHull const & other)
 }
 
 
+docstring InsetMathHull::layoutName() const
+{
+	return "Formula:" + hullName(type_);
+}
+
+
 void InsetMathHull::setBuffer(Buffer & buffer)
 {
 	InsetMathGrid::setBuffer(buffer);

src/mathed/InsetMathHull.h

@@ -47,6 +47,8 @@ public:
 	///
 	virtual ~InsetMathHull();
 	///
+	docstring layoutName() const override;
+	///
 	void setBuffer(Buffer &) override;
 	///
 	void updateBuffer(ParIterator const &, UpdateType, bool const deleted = false) override;

status.24x

@@ -37,6 +37,9 @@ What's new
 
 - Fix display of superscripts on Windows (bug 13100).
 
+- It is now possible to use inset-forall for math equations with the selector
+  "Formula" or "Formula:eqnarray", for example.
+
 
 * DOCUMENTATION AND LOCALIZATION