moved manifest generation to a seprate file and added made it support vista's access level extensions

git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@4751 212acab6-be3b-0410-9dea-997c60f758d6

Source/manifest.h

@@ -0,0 +1,24 @@
+#ifndef ___MANIFEST_H___
+#define ___MANIFEST_H___
+
+#include <string>
+
+namespace manifest
+{
+  enum comctl
+  {
+    comctl_old,
+    comctl_xp
+  };
+
+  enum exec_level
+  {
+    exec_level_none,
+    exec_level_user,
+    exec_level_admin
+  };
+
+  std::string generate(comctl, exec_level);
+};
+
+#endif//!___MANIFEST_H___