Image owns its alt text.

dw/image.hh

@@ -3,6 +3,9 @@
 
 #include "core.hh"
 
+#include <optional>
+#include <string>
+
 namespace dw {
 
 /**
@@ -115,7 +118,7 @@ public:
 class Image: public core::Widget, public core::ImgRenderer
 {
 private:
-   char *altText;
+   std::optional< std::string > altText;
    core::Imgbuf *buffer;
    int bufWidth, bufHeight;
    int altTextWidth;
@@ -145,7 +148,7 @@ protected:
    //core::Iterator *iterator (Content::Type mask, bool atEnd);
 
 public:
-   Image(const char *altText);
+   Image(std::optional< std::string_view > altText);
    ~Image();
 
    // For images, the minimal width is not well defined, and