ENH: Add macro to get HaloEvolutionTree instance
ENH: Fix ASCII output format for merger-tree
ENH: Make output less verbose
ENH: Disable print-out of the similarity matrix
BUGFIX: RelabelTreeNodes prior to dumping to ASCII
ENH: Beautify output of ASCII merger-tree somewhat
ENH: Use STL set to avoid duplicate descendants
ENH: Minor fixes and runtime checks
BUGFIX: Output halo mass
BUGFIX: Fix issue with not hashing halo IDs
ENH: Keep count of number of zombies at a timestep