GenericMonitoringTool: set correct default value for HistPath

The default value for the HistPath property was by mistake changed in commit 4a2edffa and broke the automatic booking of histograms under the tool's parent's name. Revert the default value back to an empty string and improve documentation.

Also some general cleanup of the code:

• remove irrelevant virtual
• remove declaration of InterfaceID
• remove import of std namespace as std:: was used in most places
• spell and grammar check

This merge request affects 1 package:

• Control/AthenaMonitoring

Adding @ssnyder as watcher

added Core master review-pending-level-1 labels

cc @tbold

approved this merge request

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-20292-2019-01-11-01-12
Athena: number of compilation errors 0, warnings 2
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 32121] (for remote access see the FAQ for MR reviewers)

The changes look ok. Adding review-approved label.

L1 shifter

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 83b5e89a

added sweep:ignore label