Support for extra card fields in stylesheets;

Fixed some bugs:
 - Missing choice images can crash mse.
 - The wrong style is used for making preview choice images on style panel.
FOR_EACH(x, *y.z) should now work without parentheses on linux as well.

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@389 0fc631ac-6414-0410-93d0-97cfa31319b6

src/gui/thumbnail_thread.cpp

@@ -8,6 +8,7 @@
 
 #include <gui/thumbnail_thread.hpp>
 #include <util/platform.hpp>
+#include <util/error.hpp>
 #include <wx/thread.h>
 
 typedef pair<ThumbnailRequestP,Image> pair_ThumbnailRequestP_Image;
@@ -71,7 +72,13 @@ wxThread::ExitCode ThumbnailThreadWorker::Entry() {
 			parent->open_requests.pop_front();
 		}
 		// perform request
-		Image img = current->generate();
+		Image img;
+		try {
+			img = current->generate();
+		} catch (const Error& e) {
+			handle_error(e, false, false);
+		} catch (...) {
+		}
 		// store in cache
 		if (img.Ok()) {
 			String filename = image_cache_dir() + safe_filename(current->cache_name) + _(".png");