anchor.diff:  
   ==== Weighting the wishes of nurses
   
  -In a hospital we have these constraints:
  +In a hospital nurse rostering use case, we have these constraints:
   
  +* *Double shift*: No nurse should work 2 shifts on the same day.
  +** This is more important than any other constraint, no matter how many times that other constraint is matched.
   * *Parenting nurses*: Nurses with children don't want to work on Wednesday afternoon.
   * *Young nurses Saturday night*: Young nurses don't want to work on Saturday night.
   ** This is twice as important as the _Parenting nurses_ constraint.
   * *Young nurses Sunday morning*: Young nurses don't want to work on Sunday morning.
   ** This is a third as important as the _Young nurses Saturday night_ constraint.
  -* *Double shift*: No nurse should work 2 shifts on the same day.
  -** This is more important than any other constraint, no matter how many times that other constraint is matched.
   
   Specify the `ScoreDefinitionType` and determine the score weight and level of each constraint.
   
  
positive.code: 
  * Decimal numbers (`BigDecimal`) heavily slow down the score calculation.
  * Floating point numbers (`double` or `float`) cause http://docs.jboss.org/optaplanner/release/latest/optaplanner-docs/html_single/index.html#avoidFloatingPointNumbersInScoreCalculation[errors].
  
negative.code: The `ScoreDefinitionType` is `HARD_SOFT` because we need 2 score levels.
  The weight and level for each constraint:
  
  * *Double shift*: `-1hard` for each match
  ** `scoreHolder.addHardConstraintMatch(kcontext, -1);`
  * *Parenting nurses*: `-3soft` for each match
  ** `scoreHolder.addSoftConstraintMatch(kcontext, -3);`
  * *Young nurses Saturday night*: `-6soft` for each match
  ** Because `-3soft` times `2` is `-6soft`
  ** `scoreHolder.addSoftConstraintMatch(kcontext, -6);`
  * *Young nurses Sunday morning*: `-2soft` for each match
  ** Because `-6soft` divided by `3` is `-2soft`
  ** `scoreHolder.addSoftConstraintMatch(kcontext, -2);`
  
  Any multiple applied to all of the soft or hard numbers is fine too (for example `-30soft;-60soft;-20soft;-1hard`),
  but it would increase the likeliness of overflow.
  