RFC: std.*.concept convention

[via Digitalmars-d]

Just make sure that what is implemented is what is needed.

I have gone over std.traits to see what is used in phobos and the 
following constraints appears not to be used at all:

hasNested
isAbstractClass
isBasicType
isBuiltinType
isFinalClass
isNested
isTypeTuple
isUnsafe

And these only once:

isCovariantWith
isExpressionTuple
isFinalFunction
isInstanceOf
isScalarType

...