includes :
  - change of names of the classes, dropping the 'Counter' part which is
    an implementation detail
  - rewrote Root sink in a more generic and cleaner way
  - adapted json representation of histograms to changes in the new
    monitoring merge request

Conflicts:
	GaudiCoreSvc/src/MessageSvc/MessageSvcSink.cpp

Conflicts:
	GaudiKernel/Gaudi/Accumulators/Histogram.h

Conflicts:
	GaudiExamples/options/Histograms.py

Conflicts:
	GaudiKernel/Gaudi/MonitoringHub.h

Main features of that Counter :
  - can be any number of dimensions. The dimension is its first template parameter
  - for each dimension, a triplet of values have to be given at
    construction : nbins, minValue, maxValue. These triplets have to be
    embedded into braces, as the constructor takes an array of them
  - the operator+= takes either an array of values (one per dimension)
    or a tuple<array of values, weight>. The value inside the bin
    corresponding to the given values is then increased by 1/weight
  - the Counter is templated by the types of the values given to
    operator+ and also by the type stored into the bins
  - the counter can be atomic or not and supports buffering. Note that
    the atomicity is classical eventual consistency. So each bin is
    atomically updated but bins are not garanted to be coherent when
    reading all of them back
  - profile histograms are also supported, operator+= takes one more
    value in the array of values in that case

Typical usage for an atomic 2D counter, taking doubles and using no weight :

HistogramingCounter<2, double, atomicity::full>
  counter{owner, "CounterName", {nBins1, minVal1, maxVal1}, {nBins2, minVal2, maxVal2}};
counter += {val1, val2};

Conflicts:
	GaudiKernel/Gaudi/Accumulators/Histogram.h

Conflicts:
	GaudiKernel/Gaudi/Accumulators/Histogram.h

Conflicts:
	GaudiKernel/Gaudi/Accumulators.h

Conflicts:
	GaudiKernel/Gaudi/Accumulators.h
	GaudiKernel/GaudiKernel/StatEntity.h

Closes #141

See merge request !1131

See merge request !1130

See merge request !1112

See merge request !1118

See merge request !1125

See merge request !1119

Gitlab CI authored 4 years ago and Sebastien Ponce committed 4 years ago

patch generated by https://gitlab.cern.ch/lhcb/Gaudi/-/jobs/10087220

2 main reasons :
  - make it more compliant with the way Accumulators are used for the
    other counters
  - allow to implement the fromJSON method

Note that MonitoringHub is now Gaudi::Monitoring::Hub.

Counters are now serialized in json and sent to a MessageSvcSink for printing.
This should be kind of backward compatible with current printing except that the Counter order may change.

The CounterHolder wrapper, now useless, has been dropped and counters register directly to the Monitoring::Hub
Note that his had the consequence that the Counters method of the python interface had to be dropped.
It does not seem to be used, but in case it would be needed, it can be implemented if we add a dedicated method to list counters of a given component to the Monitoringi::Hub

This allows sinks to select entities a priori, before the conversion
to JSON and thus at subscription time.

The goal was to be able to define Accumulators having several Arithmetic
types in view of an histograming counter. This had a few consequences :
  - Buffer and Bufferable counters needed a variadic template for the
    Arithmetic types
  - thus this had to be the last parameters in the template parameters
  - and thus Accumulators had also to change their template parameter
    order and put Arithmetic type(s) as the last one(s)

On the way, the inheritance diagram was slightly simplified between
Counters and Accumulators, moving the inheritance on Accumulators to the
BufferableCounter class from the user facing Counter class. This allowed
to drop a static_cast.

merge accumulators

The counter names were empty due to a too zealous std::move

See merge request !1121

See merge request !1122

See merge request !1126

See merge request !1124