In this time server will not react on any other user actions,
therefore just block UI with modal message

Means when top folder is shown, one always sees list of files displayed
Therefore when any ROOT file is opened, RBrowser just changes to
its top folder

Provide button to toggle between current directory and list of opened
files

Indicies used for handling many elements with same name in browser,
but do not (yet) supported when configuring working path

ROOT will try to find external version first and
only if fail fallback to builtin variant.

For `std::string`, we have both a TClass and a TDataType (as it is a typedef).
We should prefer the TClass (which fixes issue #7169), but not at the cost
of calling `TClass::GetClass()` first: that is just too slow. So instead,
check for "is it a datatype, not numeric, do we have a TClass?" which will
still prefer the TClass even if *also* a TDataType exists.

Provide documentation!

..rather than building the leaf name "by hand".

If an arena in the MemPoolForRooSets is not referenced anymore, it
should delete the memory it has allocated.

When doing I/O of RVec objects, TClassEdit::STLArgs was accessing
an element one after the end of a static array. asan rightly complains.

This commit fixes https://github.com/root-project/root/issues/7903,
which contains more details.

Deleting a chunk of repeated comment in the description of TH1::GetMean()

Before this patch, given a TTree with a branch with name _different_
from its leaf, e.g. like this:

```
*Br    0 :NUD_total_ADC : nud_total_adc/D
```

RDataFrame only added "branchname.leafname" to the list of available
columns (i.e. "NUD_total_ADC.nud_total_adc" in the example).

In comparison, in a similar situation `TTree::Draw` also accepts
just "NUD_total_ADC" as it assumes that the desired leaf is the
first sub-leaf of the specified branch.

With this patch, RDataFrame also considers "NUD_total_ADC" as a valid
column name as long as it has only one sub-leaf.

This fixes ROOT-9558.

* Port libAfterImage on Win64

Add `libAfterImage/CMakeLists.txt` to facilitate the port of libAfterImage on Win64

* Update CMake minimal version (thanks Oksana)

The distributed RDataFrame constructor accepts an optional `npartitions` keyword argument. Previously, if this argument was provided by the user, it set the number of partitions in which the rdf would split the distributed computations.
But then, right before starting the execution, the distributed backend implementation tried to optimize this number. In the case of Spark, an educated guess for the number of partitions would be spark.executor.cores * spark.executor.instances, that is the number of distributed nodes times the number of cores used for each node.
If we let this optimization happen just before the start of the execution, it means we completely disregard the user provided value for `npartitions`. Instead, the backend guessing at a number of partitions should happen only if the user doesn't supply one.
This commit addresses the issue by moving the call to `backend.optimize_npartitions` inside the initialization of the distributed dataframe object, plus adds a couple of tests to check the behaviour in the Spark backend.

Solved missing include of std::string referenced in error handling. Needed to compile using clang and libc++

Is now proportional to the browser size.

Setting the move constructor and move assignment operator to = default
causes linker errors because the copy assignment operator is not
implemented in the TIterator base class.

Having the RooLinkedListIter move constructor and assignment operators
work is important to keep user code compatibility.

Rename RooHistFunc::getObservables to not hide
RooAbsArg::getObservables.

Template taken from root-project/root's issue template

Before this patch, given a TTree with a branch with name different
from its leaf, e.g. like this:

```
*Br    0 :NUD_total_ADC : nud_total_adc/D
```

TTreeReaderValue failed to retrieve the leaf when the named passed
to the constructor was just "NUD_total_ADC" (while it worked fine
with "NUD_total_ADC.nud_total_adc"). In comparison, in a similar
situation `TTree::Draw` "tries harder" and it assumes that the
desired leaf is the first sub-leaf of the specified branch.

With this patch, TTreeReaderValue tries `FindLeaf` after `GetLeaf`
and as a last resort it picks the branch sub-leaf if it exists and
it is unique.

This fixes #6881.

* [core] Next bunch of changes for Win64

- Replace some more `long` types by `Longptr_t`
- Fix pointer formatting (use `%zx` and `size_t` for architecture dependent format)
- Fix several `warning C4267: 'argument': conversion from 'size_t' to 'Ssiz_t', possible loss of data`

* [skip-ci] Fix compilation warning on i386 platforms

Fix warning: format ‘%zx’ expects argument of type ‘size_t’, but argument 2 has type ‘Long_t’ {aka ‘long int’} [-Wformat=]

The custom hash table implementation RooHashTable is only used in
RooLinkedList for a transient data member. By using std::unordered_map
instead, RooHashTable gets obsolete and could be deprecated.