Emit sprite UserData into data file

src/app/commands/cmd_export_sprite_sheet.cpp

@@ -267,6 +267,7 @@ Doc* generate_sprite_sheet_from_params(
   exporter.setSplitTags(splitTags);
   exporter.setIgnoreEmptyCels(ignoreEmpty);
   exporter.setMergeDuplicates(mergeDuplicates);
+  exporter.setUserData(sprite->userData());
   if (listLayers) exporter.setListLayers(true);
   if (listTags) exporter.setListTags(true);
   if (listSlices) exporter.setListSlices(true);

src/app/doc_exporter.cpp

@@ -591,7 +591,8 @@ public:
 };
 
 DocExporter::DocExporter()
-  : m_docBuf(std::make_shared<doc::ImageBuffer>())
+  : WithUserData(ObjectType::Sprite)
+  , m_docBuf(std::make_shared<doc::ImageBuffer>())
   , m_sampleBuf(std::make_shared<doc::ImageBuffer>())
 {
   m_cache.spriteId = doc::NullId;
@@ -1256,6 +1257,8 @@ Doc* DocExporter::createEmptyTexture(const Samples& samples,
       maxColors,
       m_docBuf));
 
+  sprite->setUserData(userData());
+
   if (palette.size() > 0)
     sprite->setPalette(&palette, false);
 
@@ -1421,7 +1424,8 @@ void DocExporter::createDataFile(const Samples& samples,
   os << ",\n"
      << " \"meta\": {\n"
      << "  \"app\": \"" << get_app_url() << "\",\n"
-     << "  \"version\": \"" << get_app_version() << "\",\n";
+     << "  \"version\": \"" << get_app_version() << "\""
+     << texture->userData() << ",\n";
 
   if (!m_textureFilename.empty())
     os << "  \"image\": \""

src/app/doc_exporter.h

@@ -18,6 +18,7 @@
 #include "doc/image_buffer.h"
 #include "doc/object_id.h"
 #include "doc/object_version.h"
+#include "doc/with_user_data.h"
 #include "gfx/fwd.h"
 #include "gfx/rect.h"
 
@@ -40,7 +41,7 @@ namespace app {
   class Context;
   class Doc;
 
-  class DocExporter {
+  class DocExporter : public doc::WithUserData {
   public:
     DocExporter();