Breed setup number, max number fix

1. Removed hardcoded setup number of "100" in breed block.
2. Max number of individuals for a breed can now be specified in the XML library
   When this max number is reached, the the NetLogo simulation stops.
   A termination condition for each breed is checked in "go"
3. Some fix to ConditionDropTarget that I don't remember. May be related
   to previous fix.