Fixed: failed to re-prepare text after content dependent script changed

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@482 0fc631ac-6414-0410-93d0-97cfa31319b6

src/render/text/viewer.cpp

@@ -146,6 +146,9 @@ void TextViewer::reset() {
 	elements.clear();
 	lines.clear();
 }
+bool TextViewer::prepared() const {
+	return !lines.empty();
+}
 
 // ----------------------------------------------------------------------------- : Positions