open URLs from Emscripten

hyper.h

@@ -4026,5 +4026,9 @@ extern bool game_active, playerfound;
 
 string bygen(reaction_t h);
 
+#if CAP_URL
+void open_url(string s);
+#endif
+
 }
 

hyperweb.cpp

@@ -12,6 +12,7 @@
 #define CAP_SHMUP 0
 #define CAP_RUG 1
 #define CAP_INV 0
+#define CAP_URL 1
 #define GLES_ONLY
 
 #ifndef CAP_ORIENTATION
@@ -43,6 +44,12 @@ namespace hr {
 
 // -- demo --
 
+void open_url(string s) {
+  EM_ASM_({
+    window.open(Pointer_stringify($0));
+    }, s.c_str());
+  }
+
 bool demoanim;
 
 void toggleanim(bool v) {