Update clobberer concept

[samuelallan72]

"clobberer" naming is a little awkward here, suggesting that data is lost. No data is technically lost, since it's really summarising the statuses based on the output of a function.

The clobber classes are very verbose, when the real use is a single pure function with a certain signature. No need to add object orient programming when functions are plenty and just as clear.

Propose the following:

• rename clobberer terminology to "summarizer"
• use functions instead of classes for the clobberers/summarizers.