FIxed Assemble to not error out when there are 2 skeletons and one lord of skulls

Lord of Skulls now has images for all possible bone giants
Assemble now makes eternal before heavy (so in order of size)

Assemble correctly respects Lord of Skulls' right of uniqueness and will not merge it with the rest of the rabble!

Lord of Skulls now grants effects more gradualy and at the high end can now even affect a bone giant

such grave tree

New Map:removeEffect() method

newnecro stuff