to avoid conflicts with the other GSL (GNU Scientific Library)

The C++ GSL is downloaded from Github, exposed to the compilation of the
whole project and installed in the InstallArea.

The option GAUDI_USE_SYSTEM_CPP_GSL can be used to change the behaviour
and use the C++ GSL headers from the system.

The prototype is described in detail in
[chapter 4](https://cds.cern.ch/record/2149420).

See merge request !178

Fixes GAUDI-1241

See merge request !192

See merge request !193

As described in a private e-mail, we need this change in the code to be
able to build Gaudi for our analysis release with CMake. As in that
setup the base project to build Gaudi against is called
AthAnalysisBaseExternals, and not AtlasExternals.

See merge request !198

Fixes GAUDI-1236

See merge request !188

fixed/hidden all warnings in GCC builds

See merge request !189

https://lhcb-archive.cern.ch/artifacts/nightly/lhcb-gaudi-head/1180/summaries.x86_64-slc6-gcc49-opt/Stripping/build_log.html

Fixes GAUDI-1240

See merge request !191

The test was broken (produced a stall). This merge request introduces the migration of the test to the graph-based scheduler, which returns the test back to life.

See [GAUDI-1239](https://its.cern.ch/jira/browse/GAUDI-1239) for the work/test log.

See merge request !190

* removed CMT configuration files
* adapted scripts not to use CMT

Fixes GAUDI-1216
Fixes GAUDI-979

See merge request !186

Migrate AthenaScenario.py to use the new, graph-based scheduler. This brings the test back to life (was terminating with a stall before the migration)

See GAUDI-1077.

* master: (245 commits)
  replaced endreq with endmsg in ForwardSchedulerSvc
  fixed use of Doxygen command \deprecated
  improved deprecation warning message
  added deprecation warnings to endreq and messageService()
  Revert IncQueue_t to pointers since tbb 4.2 doesn't support it
  Fixed project_manifestproject_manifest.py to map dependency to tcmalloc (still used in CMT config) to the new name of the package (gperftools)
  flag m_ws as transient in GaudiGSLMath dictionary
  removed references to GCCXML from CMake config
  removed a couple of #ifndef __GCCXML__
  removed obsolete workaround for GCCXML + gcc 4.7
  removed unneeded references to uuid and GCCXML from GaudiPolicy requirements
  restore fix to GAUDI-1018 removed by a875c69e
  fixed scan_dict_deps.py for generated headers
  fix to GAUDI-1148 implementation
  THistSvc::getHists() fix typo
  ignore data dependencies for empty keys
  intersection fcn for EventIDRange
  Fixed barrier creation in ThreadPoolSvc for default number of threads
  Added missing IncidentProcAlg.cpp
  Removed commented parts and added testenv to Gaudi-976 test
  ...

and some related files

svn tags may still be needed without CMT.

See merge request !184