[Standard-Library] Add PositiveOperator

[BSteffaniak]

Migrated from archived repository issue.

• Source repository: FlatLang/Standard-Library
• Source issue: Make lambdas allow use of outside variables. #17
• Source URL: https://github.com/FlatLang/Standard-Library/issues/17
• Original author: @BSteffaniak
• Original created at: 2017-03-20T08:16:49Z
• Original labels: enhancement

Original Issue Body

opposite of #16