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/Script.cpp

@@ -4,6 +4,7 @@
 #include <limits.h>
 #include <SDL_timer.h>
 
+#include "Alloc.h"
 #include "Constants.h"
 #include "CustomLevels.h"
 #include "Editor.h"
@@ -48,6 +49,7 @@ scriptclass::scriptclass(void)
     textpad_right = 0;
     textpadtowidth = 0;
     textcase = 1;
+    textbuttons = false;
     textlarge = false;
 }
 
@@ -798,6 +800,12 @@ void scriptclass::run(void)
                         || key.isDown(KEYBOARD_UP) || key.isDown(KEYBOARD_DOWN)) game.jumpheld = true;
                 }
                 game.backgroundtext = false;
+
+                if (textbuttons)
+                {
+                    graphics.textboxbuttons();
+                }
+                textbuttons = false;
             }
             else if (words[0] == "endtext")
             {
@@ -2427,6 +2435,11 @@ void scriptclass::run(void)
                     }
                 }
             }
+            else if (words[0] == "textbuttons")
+            {
+                // Parse buttons in the next textbox
+                textbuttons = true;
+            }
             else if (words[0] == "textcase")
             {
                 // Used to disambiguate identical textboxes for translations (1 by default)