To preserve the connection (without introducing one when there was none),
between the content of container that is being cleared or deleted and the
list of Cleanups, we re-use fCache to inform RecursiveRemove of the
node currently being cleared/deleted.

This replaces:

‘Fix ROOT-5284 which was due to a unusual setup (in TParallelCoord) leading to only partial cleanup.’
b31faa1f

and the related commit:

‘Fix thread-safety problems with cleanup of containers’
d0b6642c

This is done by avoiding to 'Draw' those and simply Paint them as a
side effect of the TParrallelCoord's painting.

This insures that the already-written basket are not included.

Once per Snapshot call, each thread creates a TBufferMergerFile.
Once per TBB task (lifetime of an input TChain) each thread creates
a new output TTree, assigns branches to it and adds it as a clone
to the input TChain.

It is called for all action helpers right before looping.
No-op for almost all actions, at least for now.

This reverts commit e884c501.

* Fix DNN in tutorial examples

Removes the DNN option with Architecture=Standard from ordinary
and multiclass settings.

Smaller fixups output.

* clang-format

* Change default DNN implementation to CPU

    -  LogZ for violins
    -  scaling of candles and violins with respect to each other
    -  static functions for WhiskerRange and BoxRange