Content Object instances are reused
The ContentObjectRenderer creates instances for each content object to be rendered, e.g. TEXT, COA, CONTENT, etc.
However, these instances are re-used and therefore we introduced work-arounds since serialization of FLUIDTEMPLATE failed back then.
If dealing with nested record sets via RECORDS or CONTENT, reusing objects might be tricky since the parent pointer to the ContentObjectRenderer might be wrong and strange things happen.
This patch removes the pseudo singleton approach since the objects are not state-less and might lead to unexpected results in rare cases.