Add textbuttons() script command, make Violet's ENTER dialogue dynamic

Violet's dialogue now looks like this:

squeak(purple)
text(purple,0,0,2)
Remember that you can press {b_map}
to check where you are on the map!
position(purple,above)
textbuttons()
speak_active

The new textbuttons() command sets the next textbox to replace {b_map}
with the map button, and {b_int} with the interact button. The
remaining keys would be added as soon as they need to be added to
ActionSets.h as well.

desktop_version/src/Scripts.cpp

@@ -5054,9 +5054,10 @@ bool scriptclass::load(const std::string& name)
 
         "squeak(purple)",
         "text(purple,0,0,2)",
-        "Remember that you can press ENTER",
+        "Remember that you can press {b_map}",
         "to check where you are on the map!",
         "position(purple,above)",
+        "textbuttons()",
         "speak_active",
 
         "squeak(purple)",