NumberEnvelope should not implement Scalar<Double>

[andreoss]

There is no reason for NumberEnvelope to have extra method for double value.

https://github.com/yegor256/cactoos/blob/master/src/main/java/org/cactoos/scalar/NumberEnvelope.java#L115

[victornoel]

@andreoss please see #1335: once it is done, number envelope will simply delegate all the public methods of number to the wrapped number I believe

[victornoel]

@0crat assign me

[victornoel]

@0crat status

[0crat]

@0crat status (here)

@victornoel This is what I know about this job in C63314D6Z, as in §32:

• The job #1496 is in scope for 1mon
• The role is DEV
• The job is assigned to @victornoel/z for 1mon
• There is no monetary reward attached, it's a free job
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• The budget is 30 minutes/points
• These users are banned and won't be assigned:
  • @andreoss/z: This user reported the ticket
• Job footprint (restricted area)