Changed: Prepared files have _debug/_debugpcode suffix.

Added: Prepare for p-code debugging.
Added: Preparation progress
Fixed: Nullpointer in tag when character not found.

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/tags/Tag.java

@@ -917,6 +917,9 @@ public abstract class Tag implements NeedsCharacters, Exportable, Serializable {
             if (swf.getCharacters(true).containsKey(characterId) && !swf.getCyclicCharacters().contains(characterId)) {
                 Set<Integer> needed4 = new LinkedHashSet<>();
                 CharacterTag character = swf.getCharacter(characterId);
+                if (character == null) {
+                    continue;
+                }
                 if (character.isImported()) {
                     continue;
                 }