Fix mostly warning C4138: '*/' found outside of comment. But also:
warning C4101: 'hProcess': unreferenced local variable
warning C4005: 'open': macro redefinition
warning C4002: too many actual parameters for macro 'open'
warning C4091: 'static ': ignored on left of '' when no variable is declared

As more and more people are using `TGraph2D` for random cloud of points, the default drawing option implying Delaunay triangulation was not appropriate.

The default drawing option is now change to `P0`.

This commit provides the implementation of a new data source for
TDataFrame that is able to read CSV files.

Some of its features include:
- Type inference (int, double, bool, string)
- Configurable delimiter
- Quoted fields & quote escaping support
- File content stored in memory

fitsio does not work on ARM 64bits. Reverting the activation by default
of the builtin fitsio.

Adapted GDML parser to fill this information.

In TClingCallFunc use new TMutex::Reset/Restore() to clear any and all locks active before entering user code.

This is kosher because the locks were taken to forbid other threads from modifying state while this thread is modifying state.
But this thread will not modify any state while the user code is active; thus while that user code is active,
the mutex can be completely reset, and restored once the user code returns.

See 6568fb2f

Introduce macro R__LOCK_SUSPEND.

Corrects a bug when the offsets are not restored correctly.

Ideally, this would be a bitset instead -- saving that part for future
work.

Particularly some of the alignment choices were done by `clang-tidy`,
meaning this commit will fail CI but be more in-line with the formatting
of the IO subsystem as a whole.

This refactors TIOFeatures so the only public interfaces involve top-level
enums, not those specific to TBasket.

Causes small migrations throughout the source as several classes are renamed.

Additionally, addresses minor review items such as member placement and
adding some useful asserts.

- Add documentation why methods are private.
- Prefer the more efficient `TClass *cl = TBasket::Class();`

This fixes an issue where offset-generation-skipping was incorrectly disabled
for TLeafO (which is Bool_t, not TObects!) but enabled for TLeafElement and
TLeafObject.

It is intended that more fine-grained whitelisting of objects in TLeafElement
and TLeafObject will be done in the future.

This provides a new method in the TTree class for probing IO features.
The API looks like this:

```
ROOT::Experimental::IOFeatures settings;
settings.Set(TBasket::EIOBits::kGenerateOffsetMap);
treeptr->SetIOFeatures(settings);
```

Note this explicitly marks these as belonging to the `Experimental` namespace,
has no externel setter, and denotes it as belonging to the IO subsystem.

If fLeafCount is a nullptr, then an offset array will not be requested.
Hence, we remove the code corresponding to this use case.

Additionally, removed various default debug statements.

First version of this to pass the unit tests.  Debug statements remain;
still need to change offsets to event sizes.