New class evolution for Archmages: High Thaumaturgist, that focuses on using and enhancing beam spells

thanks arhont !

Memory leak fixes



See merge request !640

When there is possible negative life the player's healthbar will now account for it and add a visual marker at the "0" health point too

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