Cleanup
Merge branch 'master' of https://root.cern.ch/git/root
Revert "Revert "Enable autoloading of classes in namespaces""

This reverts commit 46a0435a1090a711c3b4eae60529fa907b89570d.
Second try to silence warning cast from pointer-to-object to pointer-to-function.
Improve encapsulation.
Move ValueExtractionSynthesizer specifics to its implementation.
Get rid of references to the interpreter class in the ExecutionContext.
Disable unused clang parts to reduce build time and size.
Remove remaining traces of llvm::Type from cling::Value.
Remove now unused Interpreter::getLLVMType().
Revert "Expose QualType to llvm::Type codegen-ing."

This reverts commit f3bbbd62d108dafc1cda690d455b808b386942e2.
Not needed anymore as we don't use llvm::ExecutionEngine::runFunction() anymore.
Remove now unused llvm::Type from cling::Value + dependencies.
Workaround cling limitation (ignoring -Wno-xyz) with pragmas

transforming -Wno-xyz into a diagnostic pragma which instructs cling
to ignore the -Wxyz warnings.
Fix printout when PieceWiseInterpolation evaluates to negative value ( ROOT-5555 ).
Print only in debug mode
Fix for ROOT-5416
Fix copy constructor and assignment operator for TGraph2D. DO as for TH1, copy everything except list of functions.
Implement copy constructor and assignment for TGraph2DErrors.
This fixes ROOT-5470
SIGINT handler's sketch
Incorporate vdt

add the vdt mathematical library to root.
https://svnweb.cern.ch/trac/vdt
The library offers extremely optimised, vectorisable and approximate
implementation of the most commonly used functions in HEP.

Points relevant to the integration:
1) Add a stamp file in the lib directory to transparently use the
Makefile infrastructure
2) Add a comprehensive test leveraging the CMake infrastructure
3) The build of vdt as library ready to preload will be delegated
to a script
4) The array signatures have been removed for the moment in favour
of a header only solution
Remove more redundant code
Remove llvm::Type from the cling::Value
Remove leftovers from merge
More merge fixups.