PE: Implement a new scoring system for rsc_(co)location constraints

• If r1 is collocated with r2, then r2 is allocated first
• If r1 is collocated with r2 and r1.priority >= r2.priority, then

r1's node scores are adjusted according to the following formula:

r1.score[node] += r2.score[node] * collocation.score / INFINITY

rsc_location scores are only applied to one member of a colocated group

Mercurial revision: 18ef91d6fe62341b2f51860b5cbacc2defac1d8e