Make ListX, SetX, SumX and ProductX support lists

[ChrisJefferson]

Please make sure that this pull request:

• [X ] is submitted to the correct branch (the stable branch is only for bugfixes)
• [X ] contains an accurate description of changes for the release notes below
• [X ] provides new tests or relies on existing ones
• [ X] correctly refers to other issues and related pull requests

Tick all what applies to this pull request

• [X ] Improves and extends functionality

Write below the description of changes (for the release notes)

Extend ListX, SetX, SumX and ProductX to support arbitrary lists, as well as collections.

[codecov-io]

Current coverage is 49.30% (diff: 100%)

Merging #903 into master will increase coverage by 0.11%

@@             master       #903   diff @@
==========================================
  Files           423        423          
  Lines        229156     229156          
  Methods        3448       3448          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits         112717     112980   +263   
+ Misses       116439     116176   -263   
  Partials          0          0          

Powered by Codecov. Last update d60d5c3...78a291e

[ChrisJefferson]

Now updated with complete test coverage

[fingolfin]

This looks sensible to me. And I just had a look at the documentation for ListX, and it actually explicitly states that it expects "a list or collection". So I am confident this it the right things to do!