CLEANUP: Several details around findnsols/4,5.
MODIFIED: findnsols/4,5:
  - generate a domain error if N < 0.
  - be deterministic if Goal leaves no choice while chunk is complete.
  - Allow for dynamically changing the chunk-size.
Updated pengines.
FIXED: Colour handling of floating point numbers.
Updated pengines
improve documentation
Updated pengines
DOC: Improve some summary strings