Fix SNBT Parsing and writing of single quoted strings, and strings with quotes or single quotes within.

lib/nbt/Tag.dart

@@ -67,6 +67,12 @@ enum TagType {
         break;
       }
 
+      if (val == "'") {
+        reader.next();
+        isQuoted = true;
+        break;
+      }
+
       if (val == '{') {
         ret = TagType.Compound; // Detected a CompoundTag
         reader.next(); // Consume '{'
@@ -251,7 +257,13 @@ abstract class Tag {
     TagType type = TagType.getStringifiedTagType(string);
     Tag tag = Tag.makeTagOfType(type);
     tag._key = name;
-    tag.readStringifiedValue(string);
+    try {
+      tag.readStringifiedValue(string);
+    } catch (E, stack) {
+      print(E);
+      print(string.getSnapshot());
+      print(stack);
+    }
 
     return tag;
   }
@@ -286,6 +298,14 @@ abstract class Tag {
     }
   }
 
+  bool shouldUseSingleQuotes(String value) {
+    return value.contains("\"");
+  }
+
+  bool shouldEscapeSingleQuotes(String value) {
+    return value.contains("'");
+  }
+
   void writeStringifiedValue(StringBuilder builder, int indent, bool isList);
   void readStringifiedValue(StringReader reader);