rename vblend to vpermute2, add some comments on the conventions and the reason for them

rename vblend to vpermute2, add some comments on the conventions and the reason for them

This merge request affects 1 package:

• Control/CxxUtils

This merge request affects 2 files:

• Control/CxxUtils/CxxUtils/vec.h
• Control/CxxUtils/test/vec_test_common.h

Adding @ssnyder ,@rbianchi as watchers

added Core master review-pending-level-1 labels

CI Result SUCCESS (hash 961ce335)

	Athena	AthSimulation	AthGeneration	AnalysisBase	AthAnalysis	DetCommon
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
AthAnalysis: number of compilation errors 0, warnings 0
DetCommon: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 44587]

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

mentioned in commit abd97c3c

merged

added sweep:ignore label