We get races if all threads access the same TEntryList reference.
This reverts commit f0556c0b,
and adds a comment so we remember in the future.

this new VDT version does not assume that the Python interpreter is called
python but rather relies on CMake to invoke the right executable.

Was no longer used, there are alternatives

There is alternative with TRootSniffer::Produce(..., std::string&)

There is alternative signature with shared_ptr as argument

There is alternative with shared_ptr<> as argument

We now actually do a Prefill on the requested entry (rather than learning just one branch)

unique_ptr can be nullptr too sometimes *and* anyway TStreamerInfo::Build does not make the same restriction.
The mismatch lead to baffling error message like:

Warning in <TStreamerInfo::BuildOld>: Cannot convert A::h from type: B to type: B, skip element

This solves one of the problems seen in https://sft.its.cern.ch/jira/browse/ROOT-9702.

Dedicated branch now created in JSROOT repository

Add a test of TFormulal::Print