cleanup spahm/rho

[briling]

• remove 01_bind.py
• fix rep completion
• check regroup_symbols in utils.py
• renaming of bond.py and removing of atom.py (spahm-rho unification #105)

[YAY-C]

@briling should we add the renaming of bond.py and removing of atom.py (mentioned in #96) here and the upcoming PR ?

[briling]

yeah we can combine this issue and #105