This patch prepares the infrastructure to be able to work with a
global module index.

This gives possibility to call FitResult::GetConfidenceIntervals for the fits done using Fitter::FitFCN. For example in case of TBinomialEfficiencyFitter. 
This commit fixes ROOT-7790.
The tutorial TesBinomial.C has been updated to compute as example the confidence interval of the fitted function. 

Each node of the computation graph initializes the RCustomColumns
in its RBookedCustomColumns table. This is necessary as there is
no central entity that knows all booked custom columns and can
initialize them all in sequence.

However, this means that a given RCustomColumn can have its `InitSlot`
(setup) and `ClearValueReaders` (teardown) method called multiple
times per task. This is not a logical error (these methods are
idempotent) but it is wasteful.

This commit introduces a simple flag that is set/reset at setup/teardown
and is checked before performing any operation on the RCustomColumn.

Previously, the check was performed at the beginning of every
task, for every node. This check becomes expensive with a large
(O(10k)) number of custom columns.

The 4th parameter was wrong, although harmless: it is meant
to be a list of names of input columns, which is an empty list
for rdfentry_ and rdfslot_. The names passed were disregarded
anyway, as the lambda expression did not take any inputs.

Continuation of a Google Summer of Code 2018 project.

Note: Commented out source files are in the source directories,
but were not used before. Adding them makes TMVA compilation fail.

Since CUDA has special requirements for the compiler and C++ standard,
we should require users to enable this by hand to avoid unnecessary
configuration failures with recent compilers or because CUDA has no
support for C++17.

FindX11.cmake already has the path being added here listed before
/usr/include, so we do not need to add it. XQuartz headers are
actually in /opt/X11/include, and /usr/X11R6 is a link to /opt/X11.

Before calling ROOT_APPLY_OPTIONS(), no options are set yet, which
means the else() is always taken here, turning off all tmva components
unless one specifies -Dtmva=ON on the CMake command line.

Can cause unnecessary extra linking to system libraries. We should
add linking libraries directly to each target that needs it.

The OSX linker stores the symbols in a shared library by adding an
extra "_" as prefix to the mangled name. However, the llvm JIT gives
us a unix mangled name.

This patch adds a the missing extra prefix if we are on OSX.

The old location excluded them only from the modulemap however
rootcling still tried to build a module for them.

the simulated annealing minimizer algorithm from GSL.
This fixes ROOT-4880

Checking with output plot the result obtained now it is correct, while it wasn't really before. Onother crossing points for the limit was found but at a lower valuie.

Fix also root finding in roostats in hypotestinverter that edges are returned when interval does not contain a root.