Fix the configuration to find Blas and decide either to build CPU or GPU architecture. Define this in RCondifure.h

Improve backdrop test

This reverts commit b0adf47a.

This reverts commit 4ac3743a.

Fix compilation errors with the latest version of Visual Studio (15.7.0)
- Prevent compilation error G47C585C4: STL1000: Unexpected compiler version, expected Clang 6 or newer
- Fix exported symbols

* CMake 3.9 is now installed by default on Travis: https://docs.travis-ci.com/user/build-environment-updates/2017-12-12/
* Clang 5.0 (and clang-format, clang-tidy) are now installed on Travis
* Just get clang-format-diff.py
* Move extensive setup to .ci/*
* Fix usage of yaml keys
* Avoid if statements by using build matrix entries
* Note clearly that one block of code will not run
* Remove comments about interleaved macOS

"VecOps" was hardcoded in TCling.cxx and VecOps were renamed to
"ROOTVecOps" afterwards.

Allows renaming a TChain, without this the registration in the list of specials,
list of cleanups and list of datasets are corrupted

This allows for testing that there is no unexpected duplicate (duplicates are unavoidable in case
of 'multiple' pass throught the TTree cluster(s)).

See 3ee42f5a7d

This reverts commit 915d488a.

The replacement prevented the recording of the data member documentation
strings for the content of the library and thus was breaking the I/O, in
particular transientness, for thoses classes, eg TTreePerfStats.
(See below for an example).

This seems to be due to the fact that we need/must not add __ROOTCLING__
during the parsing that will be recorded in the the pch, see in
core/dictgen/src/rootcling_impl.cxx line 4334:

    // We do not want __ROOTCLING__ in the pch!
    if (!onepcm) {
       clingArgs.push_back("-D__ROOTCLING__");

So, at least for now, we need to keep using __CINT__ for the LinkDef.h
of the libraries included in the PCH.

See:

root [0] TClass::GetClass("TTreePerfStats")->GetStreamerInfo()->ls()

StreamerInfo for class: TTreePerfStats, version=7, checksum=0x1f86d003
  TVirtualPerfStats BASE            offset=  0 type= 0 ABC for collecting PROOF statistics
  int            fTreeCacheSize  offset= 16 type= 3 TTreeCache buffer size
  int            fNleaves        offset= 20 type= 3 Number of leaves in the tree

vs

root [0] TClass::GetClass("TTreePerfStats")->GetStreamerInfo()->ls()

StreamerInfo for class: TTreePerfStats, version=6, checksum=0x84181ab4
  TVirtualPerfStats BASE            offset=  0 type= 0 ABC for collecting PROOF statistics
  int            fTreeCacheSize  offset= 16 type= 3
  int            fNleaves        offset= 20 type= 3

This is to avoid changes in the behavior near a release of which options
that get enabled by default when cmake is called without arguments, as
well as which packages cause a failure when fail-on-missing=ON (packages
with builtins should not cause failure).

This partially reverts commit aad5a3bb.

This reverts commit 901f8d96.

This reverts commit 970be6a2.

This reverts commit 79150a40.

This reverts commit d7b7eb83.

This reverts commit fedad08a.

This reverts commit 2711d2fb.

This reverts commit 48aeaef8.

This reverts commit eee4144c.

This reverts commit 87d21924.

This reverts commit 2c93f75a.

This reverts commit df5d33a7.

This reverts commit 51b155d8.