std.experimental.checkedint Formal Review

[Robert burner Schadek via Digitalmars-d]

It is time to formally review Andrei's checkedint.

Checkedint is a wrapper for integer types that allows to run code 
on over/underflows, define NaN like init states and more.

The PR can be found here:
https://github.com/dlang/phobos/pull/4613

The dub package can be found here: (1)
http://code.dlang.org/packages/checkedint_andralex

The docs can be seen through CyberShadow/DAutoTest in the PR.

Due to the holidays the review period is extended to **2016-01-05 
(AoE)**

Please browse through the comments of the PR to keep this 
discussion DRY.
Style nitpicks should be made on github.

The discussion in this thread should be about the design and 
phobos inclusion worthiness (PIW) of the module, not about where 
to place braces.


(1) Andrei, please make sure they are in sync.