This is mostly to make anti-virus (virustotal.com) happy with Windows binaries and prevent false positives. But it is also nice to have proper ROOT icon and meta-information in the executables themselves

In case ROOT is sourced via the config script, the variable
JUPYTER_CONFIG_DIR tells the jupyter server where to look for the
jupyter_notebook_config.py. This file contains the path to JSROOT in the
build directory pointed to by ROOTSYS.

* Add preprocessor flag in RConfigure.h for pymva and rmva

* Enable RMVA when R is found and tmva is on

* Update CNN and RNN tutorial to work also when ROOT is built without Pymva

When -Ddev=ON specified, R__LESS_INCLUDES is defined
It will be used to reduce includes which are exposed to the public.
While such changes can have side-effects on user code, 
option is off by default.

In order to avoid {namespace std} interfering with following include files,
when generating a dictionary file add the {using namespace std;} only after
GenerateNecessaryIncludes method is called.

Since many legacy root header files do require this global {using namespace std;}
to complete the tests, old behaviour is kept by default and the global
{using namespace std} can be avoided by adding -noGlobalUsingStd to rootcling invocation.

Allow passing ACLiC RootCling flags via .rootrc (Vassil)

Since we are getting rid of the subdirectories, the first step for what
concerns the environment configuration is going back to the pre-existent
situation.

Define a new configure preprocessor flag R__HAS_CUDNN that is set when Cudnn is found
If not set exclude all cudnn code in CudaTensor.cu and make sure that dense layers works in GPU without cudnn
Fix also the CNN for native Cuda. A bug was present creating the input tensor with TCuda architecture

Now ROOT/TMVA should compile when Cuda is on (tmva-gpu) and cudnn is not found.

Add also a new  cmake build option: cudnn. The option is by default enabled when cudsa is enabled.

[Exp PyROOT/thisroot.sh] Added missing part of the path that did not allow 'out of the box' correct source

Checking only for the existance of 'CMakeFiles' without including
ROOTSYS in the path was causing the addition of wrong paths in case of
out-of-the-box source

[Exp PyROOT/thisroot.sh] EXP_PYROOT variable passed by command line that covers the case of instalallation

N.B.: will go away once experimental will become the default

Due to the way in commit 4700 we changed how clean_environment works (we
get rid of $pyroot_dir and all the cases for lib/python*), we got back
to the ZSH problem solved in commit 4693.

In order to solve it once and for all, we proceed like the following: at
the beginning of the clean_environment function we check whether we are
using ZSH; if so, we check if nonomatch is enabled; if it is already
enabled (behavior that we want), we don't do anything; if it's not
enabled, we enable it and set a variable that reminds us to disable at
the end.

[Exp PyROOT/thisroot.sh] Correctly update environment variables in installation with and without customized CMAKE_INSTALL_PYROOTDIR

Due to the way it works by default, sourcing a root version built with
current pyroot was failing, due to the fact that operations such as:

for pyroot_libs_dir in ${old_rootsys}/lib/python*

were performed both in experimental and current.

In zsh, if a path specified with '*' is not found, an error like the
following is raised:

clean_environment:20: no matches found: zsh_build/lib/python*

and the program aborts, without sourcing anything.

With these change, such loops are performed only if root is built with
pyroot experimental.

Here we make all the changes necessary to enable the pyroot experimental
related variables and paths only when we are in pyroot experimental.
This can easily be reverted once PyROOT experimental will be the
default.

Here we make the necessary changes to allow the user to choose a specific
PyROOT build directory when source thisroot.sh.
Source a specific Python version by calling:

$ ROOT_PYTHON_VERSION={version_number} source bin/thisroot.sh

If ROOT_PYTHON_VERSION is not provided, the last built version is sourced.
If the ROOT_PYTHON_VERSION is not valid (i.e. the corrispondent build does not
exist) a message is printed and no action is performed.

The 'thread' option could not be disabled, so it has been removed
by commit 8e0e72cf. However, its
value was being used in root-config in a way that was not caught
by the initial inspection. The effect was to drop the -pthread flag
from root-config --cflags, which is now fixed by this commit.

It was never expanded in cmake. Allowing externally provided llvm resource
can be dangerous because of compatibility reasons.

The aclocaldir is not for locale-dependent data, but for installing m4
macros. However, the obsolete root.m4 macro file has been removed from
the repository in commit a673ee7b, so these variables are unnecessary.

This is very special component of THttpServer, which is not used up to
now. Make it as cmake option and disable by default. Only when really
needed, user can enable it.

This is to ensure consistent behavior, since someone including ROOT
headers may forget to define R__HAVE_CONFIG when compiling against ROOT.

This option is ported from ROOT 5.x but disabling it makes
compilation break since a long time. Fixes: ROOT-9449.

The new cmake option `dataframe` enables building the ROOTDataFrame
library and takes care of implication on the build system. The option is
enabled by default unless a 32bit system is detected.

This reverts commit a7d45455.

This is done by taking the check of fUniqueID and the assignment to fBuits
into a separate function and by including this function in the header
*but* marking it as "noinline" to prevent its inlining and preserve a
way to suppress the valgrind warning.

Introducing the macro R__NEVER_INLINE which expands to

   inline __attribute__((noinline))

The performance degradation is less than 10% for a case doing
only creation and destruction of TObjects.

This reverts commit 83e5d9f45c76914118501652e0c53ff56793fefe.