added check to Transaction that prevents a pattern where the transaction object is re-used (this might hint to a usage pattern where a transaction is recursively build during a commit, causing the ongoing "running" transaction to be restored as "current");
added check to Transaction that prevents a pattern where the transaction object is re-used (this might hint to a usage pattern where a transaction is recursively build during a commit, causing the ongoing "running" transaction to be restored as "current");

vrvis/aardvark,vrvis/aardvark,vrvis/aardvark.base,vrvis/aardvark.base