Implement "unique" constraint and other constraints?

[roll]

Overview

Unique constraint e.g. in Python when we iterating table rows - https://github.com/frictionlessdata/tableschema-py/blob/master/tableschema/table.py#L94-L104

Also to be sure we support all list of constraints:

• [x] required
• [ ] unique
• [ ] minLength
• [ ] maxLength
• [ ] minimum
• [ ] maximum
• [ ] enum

[danielfireman]

Great catch. The current version of tableshema-go is not supporting constraints.

[danielfireman]

Opened issues for specific implementations. It is easier to track and get contributions.