- move Gaudi::Funtional to GaudiFunctional subdir
  - headers are now under "Gaudi/Functional"
  - legacy GaudiAlg corresponding header redirect to the new ones
- replace GaudiAlgorithm with Algorithm wherever possible in tests and
  utilities
- add Gaudi::Sequencer basic implementation to replace GaudiSequencer
- move GaudiAlg specific tests, examples, dictionaries and Python modules
  to GaudiAlg subdir
- add CMake option GAUDI_ENABLE_GAUDIALG to allow skipping GaudiAlg
  (default to true)
- minor fixes and clean ups

gaudi_add_pytest is used to declare pytest tests. Each of the test
files discovered by pytest are mapped to one ctest test, to be able to
run them in parallel.

Tests are collected when ctest is invoked and/or at build time, and only
in case changes are detected in scanned files.

it is useful when Gaudi is used as a sub-project

At build time the requested optional dependencies are "REQUIRED", while
they are just RECOMMENDED when in GaudiConfig.cmake is used in
downstream projects.

Which needs to be done carefully in case of some compiler/platform
combinations.

Thomas Cluzel authored 4 years ago and Marco Clemencic committed 4 years ago

see https://its.cern.ch/jira/browse/LBCOMP-23



Co-authored-by: Marco Clemencic <marco.clemencic@cern.ch>