Removal of UniqMap module

[Matthew Pickering]

Hi,

I noticed that the UniqMap module was removed from the tree

See 1c7c6f1afc8e7f7ba5d256780bc9d5bb5f3e7601

Why was it removed? I needed it today and now I am unsure what the
suitable replacement is.

As a general point, please can we stop with these annoying
refactorings which delete unused code
and move around definitions for no clear purpose. The amount of churn
on the code base has wasted me a lot of time recently.

Cheers,

Matt