Remove prefix to make shrinker ocurrences clearer

Removing 'shrinker' prefix from some messages in order to make shrinker occurrences clearer.

Example:
shrinker:       processing request to free %08d bytes.
                starting with %d things.
                finishing with %d things.
                %08d bytes of memory were freed!
Merge pull request #10 from raphaelsc/patch-4

Remove prefix to make shrinker ocurrences clearer